Cable/DSL

Navas Cable Modem/DSL Tuning GuideTM

The Screen Savers Site of the Week

TechTV
Appearances
by John Navas

Cable Modem and DSL (e.g., ADSL, G.lite, IDSL, SDSL) tips on increasing speed, enhancing security, fixing problems, sharing a connection, and more.

Copyright 1999-2012 The Navas GroupSM, All Rights Reserved.
Permission is granted to copy for private non-commercial use only.

Posted as <http://cable-dsl.navasgroup.com/>. 

Contents

Important Notes:


Quick and Easy!

If you want to skip all the discussions and technical explanations, and just cut to the chase, most people only need to do the following to optimize and secure their Cable Modem or DSL connection:
  1. Before you start
  2. Increasing TCP Receive Window, Method 2
  3. Disable File and Print Sharing (Security on Cable Modem or DSL, Case A)

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Before you start

If you are running Windows 95 (rather than Windows 98/Me, Windows NT/2000/XP, or something other than Windows, although see note below for Windows 98), the first thing you should do is update networking to the latest version by installing:
  1. Windows Socket Update - Kernel 32
  2. Dial-Up Networking 1.4 Upgrade (includes general networking fixes, not just dial-up support; also applies to Windows 98)
  3. Windows Socket 2 Update
  4. Microsoft DUN 1.3 and Winsock2 Year 2000 Update

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Increasing TCP Receive Window for Microsoft Windows 95/98/Me/NT/2000/XP

Q: How do I get the maximum possible DSL or Cable Modem speed under Windows 95/98/Me/NT/2000/XP? Should I use one of those tweaking programs?

A: The only Windows 95/98/Me/NT/2000/XP network setting that has any real effect on DSL or Cable Modem speed is the TCP Receive Window size, which can be controlled with the following Registry settings:

Everything else commonly recommended (e.g., TTL) are urban myths that won't help.

To modify your TCP Receive Window size, use one of the following two methods:

Method 1

Save the appropriate four (4) lines of text below to your Desktop in the file name indicated (or just click the accompanying link while holding down the Shift key to download the file), and then double-click on the resulting file to add the setting into your Registry. However, this does not clean out any dial-up modem "tweaks" that might interfere with Cable Modem/DSL speed -- if you need to do that, use Method 2 (preferred).
Normal Latency*
(e.g., normal DSL or 2-way cable)
32K Window
Windows 95/98/Me
TCPRW32K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
"DefaultRcvWindow"="32767"

Removal**
TCPRWundo.inf
Windows NT
NTTCP32K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"TcpWindowSize"=dword:00007fff

Removal**
NTTCPundo.inf
Windows 2000/XP
2KTCP32K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"GlobalMaxTcpWindowSize"=dword:00007fff

Removal**
2KTCPundo.inf
High latency*
(e.g., poor DSL or 1-way cable)
63K Window
Windows 95/98/Me
TCPRW64K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
"DefaultRcvWindow"="65535"

Removal**
TCPRWundo.inf
Windows NT
NTTCP64K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"TcpWindowSize"=dword:0000ffff

Removal**
NTTCPundo.inf
Windows 2000/XP
2KTCP64K.REG
REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"GlobalMaxTcpWindowSize"=dword:0000ffff

Removal**
2KTCPundo.inf

* Latency: Check latency with 'ping' (or 'traceroute') to a number of distant hosts and use the highest typical value. (See Important Note below under "Latency") Reasonable rough rules of thumb are that low latency is below 100 ms, and high latency is above 200 ms (with normal latency in the middle).

** Removal: INF files are provided that will automatically remove these Registry entries, restoring default behavior.  Click the link to start the download; save the INF file to your desktop; right-click on it, and then choose Install to run it. The INF file can then be discarded. Reboot your system for the change to take effect.

Method 2

Notes:
  • Now supports Windows NT (but not yet Windows 2000/XP or Windows Me -- use Method 1 for Windows 2000/XP or Windows Me).
  • 11 Dec 2000: Report received that F-Secure Anti-Virus claims the set_rwin.vbs script (below) contains a virus. This is a false positive -- the script contains no virus.

As an alternative to the fixed Registry settings in Method 1 above, a single Windows 95/98/NT script provides not only an adjustable TCP Receive Window size, but also the ICS fix (see Q230116 "Slow Transfer Rates with ICS and High-Bandwidth Devices") and the ability to clean out any dial-up modem "tweaks" that might interfere with Cable Modem/DSL speed (see Important Note below under "MTU").

To run this script you must have Windows Script Host/Windows Script 5.0 or higher installed. (If it is installed, you will have WSCRIPT.EXE in the WINDOWS directory with a version number of 5 or greater.)

Click  while holding down the Shift key to download set_rwin.vbs. (1.20 is the current version number. If you have problems downloading the vbs file, a zipped version is also available for download as set_rwin.zip; you must unzip the file with a utility like WinZip after downloading.) Save the downloaded file to your Desktop (and unzip if zipped); then double-click to run it. If the script does not run correctly, your Registry may be corrupted; try downloading and reinstalling Windows Script Host. (Report problems to John Navas.)

This script can also be used to restore all settings to default values (i.e., to remove the Receive Window tweak).

Important Notes:

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TCP Receive Window in Microsoft Windows Vista (new!)

Windows Vista has a new feature called Receive Window Auto-Tuning that is supposed to adjust the TCP Receive Window size automatically. While it works properly much of the time, it can cause problems in some situations:

To resolve problems with Receive Window Auto-Tuning in Windows Vista:

  1. First try autoTuningLevel=restricted (as described in the first reference above)
  2. Then try autoTuningLevel=highlyrestricted (as described in the first reference above)
  3. Also try autoTuningLevel=disabled (as described in the first reference above)
  4. It may also help to set rss=disabled (RSS stands for Receive-Side Scaling)

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Increasing TCP Receive Window for Apple Macintosh

Caveat: The following information has not been tested by this author. USE AT YOUR OWN RISK.

TCP Receive Window can be adjusted with the "tcp_rwin_mss_multiplier" setting of the OT Advanced Tuner from Sustainable Softworks. This author suggests a starting value of 20. You may need to experiment to find your own optimum setting(s). For more information, see:

Note: This author has no connection to Sustainable Softworks.

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Why TCP Receive Window Matters

TCP is a packet-based protocol where data is transmitted in variable-sized blocks, typically with a maximum size of 500-1500 characters (usually 1500 characters for Cable Modem or DSL). Two important characteristics of the TCP protocol:

Packet Acknowledgments
In order to insure delivery of each packet, the receiver must acknowledge successful receipt by sending a special acknowledgment packet to the sender. If the sender does not receive the acknowledgment packet within a certain time limit, it assumes the packet has been lost and retransmits it (up to a retransmission limit).
Receive Window
If each data packet had to be acknowledged before another could be sent, then performance could suffer due to the delay time needed for the data packet to reach the receiver plus the time needed for the acknowledgment packet to get back to the sender. To avoid this delay, the sender is allowed to keep transmitting data packets prior to receiving acknowledgments up to a maximum "window" size advertised by the receiver, normally large enough for several packets. The larger the window, the more packets that can be sent before needing an acknowledgment; however, larger windows can require more packets to be retransmitted when a transmission error occurs. Hence, the receive window size needs to be large enough to keep data flowing continuously, but not excessively large.
The TCP Receive Window has a default value of only about 8K bytes in Windows 95/98/NT, and about 16K bytes in Windows Me/2000/XP, which is adequate for relatively slow dialup modems and for high-speed networks with relatively low latency (e.g., less than 20 milliseconds). Increasing the TCP Receive Window above the default settings (e.g., to 32-63K) can substantially improve throughput on high-speed (e.g., Cable Modem or DSL) connections where there is higher latency (e.g., 100-200 milliseconds), as is often the case on the Internet, particularly over long network paths. (Increasing the TCP Receive Window will usually not have an adverse effect on other connections.)

As an example, consider the case of downloading a file at 100 kilobytes per second from a remote server over a Cable Modem or DSL connection. The default TCP Receive Window of about 8K bytes will be consumed in only about 80 milliseconds, which is often less than the round-trip latency on the Internet. At this point the sender has to stop sending until an acknowledgment that data was received comes back from the receiver. With a TCP Receive Window of 32K bytes, the sender can continue for as long as 325 milliseconds without an acknowledgment, which should permit uninterrupted data flow even when latency is 100-200 milliseconds or more. (With a TCP Receive Window of 63K bytes, the sender can continue for as long as 650 milliseconds.)

See animations in TCP Receive Window Illustration.

The following table can be used to determine the minimum TCP Receive Window size needed for given (1) downlink speed (see "How to check your connection speed") and (2) latency:

Minimum TCP Receive Window Needed

 

 

Downlink speed in kilobits per second

500 1000 1500 2000 2500

Latency
(end to end)
as measured
by 'ping' in
milliseconds

50 2K 5K 7K 10K 12K
100 5K 10K 15K 20K 24K
150 7K 15K 22K 29K 37K
200 10K 20K 29K 39K 49K
250 12K 24K 37K 49K 61K

Windows 95/98/NT default

8K

Windows Me/2000/XP default

16K

Navas recommended setting

32-63K

This TCP Receive Window tweak is needed because Windows 95/98/Me/NT/2000/XP do not do a proper job of automatically adjusting the TCP Receive Window size to accommodate different network speeds and latencies. (Other operating systems may do a better job and not need this kind of tweaking; in this author's tests, for example, Red Hat Linux 6.0 performed as well without tweaking as Windows 98 with tweaking, even though Linux was running on much slower hardware.)

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Dealing with latency, packet loss, and/or upload speed

Latency and packet loss can be measured with the 'ping' command. Open a Command window and type "ping remotesite" where remotesite is the domain name or IP address of the remote server (e.g., "ping www.yahoo.com"). For more information, see "How to find out what's slowing you down".

Latency

In basic terms, latency is the time needed for a round trip over the Internet between two points (e.g., your computer and remote host). Latency is usually not a problem with a proper TCP Receive Window (see "Why TCP Receive Window matters"), but high latency can adversely affect interactive applications such as on-line real-time gaming. High latency is usually caused by Internet routing and/or congestion issues. There's usually not much you can do about such issues other than complaining or even switching service providers. However, if your latency is is higher due to "interleaved mode" then it may be possible to get some improvement. See "What is 'Interleaved Mode?'"

Packet Loss

Data is transmitted over the Internet in blocks known as packets. Packets usually reach their destination, but may be lost due to such things as network congestion. When a packet is lost, it takes a significant amount of time for: the receiver to notice that a packet has been lost; the receiver to notify the sender to resend the lost packet; and packet(s) to be retransmitted. Ideally zero, packet loss should be less than 1%; packet loss over 5% is generally considered severe. There's usually not much you can do about packet loss other than complaining or even switching service providers. There is no adjustment that you can use to decrease packet loss. However, if you are suffering from packet loss, the adverse effects may be reduced by decreasing the TCP Receive Window. See "Why TCP Receive Window matters".

Upload Speed

Your upload speed (sending to a remote host) will be limited by your Internet connection, network path, and remote host. It may also be limited by capping (see "How the Upstream Cap can affect Downstream Speed"). It is not limited by settings you can adjust; i.e., there is no adjustment that you can use to increase upload speed.

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Why tweaking TTL won't increase speed

TTL stands for Time To Live, the maximum number of seconds that a packet is allowed to be on the Internet before it is destroyed as undeliverable. However, as a practical matter TTL is really the maximum number of hops that will be followed, since TTL is decreased by at least 1 on every hop, and most hops are less than 1 second (usually much less).

The purpose of TTL is to guard against impossible or erroneous routing (e.g., loops where a packet would otherwise go around and around forever); for example, given an intended route from A to E:

A -> B -> C -> D -> C -> D -> C -> D -> C -> D  ...  

In this case (looping between C and D) the TTL counter would run down to zero and expire, bringing an end to the loop:

32   31   30   29   28   27   26   25   24   23 ... 0

The objective is to have TTL large enough that packets will always reach their destinations over valid routes even with lots of hops, but not so large that excessive resources are wasted when erroneous routing (e.g., looping) is encountered.

In Windows 95 TTL defaults to 32. In almost all cases this is sufficient, since normally the number of hops will be less than 32 (usually much less). However, if and when the number of hops does exceed 32, then packets won't reach the intended destination (and communication won't be possible at all). To guard against unusual cases where the number of hops does exceed 32, default TTL was increased to 128 in Windows 98.

The bottom line is that TTL is not a parameter that increases or decreases speed. If packets are reaching the intended destination, then increasing TTL won't have any effect at all. TTL only matters when packets aren't able to reach the intended destination over a valid route; i.e., when there is no speed at all.

You can check the number of hops on a given route in Windows by using "tracert" (Microsoft-speak for "traceroute") in a command window; e.g.,

>tracert -d www.yahoo.com

Tracing route to www.yahoo.akadns.net [204.71.202.160]
over a maximum of 30 hops:

  1   105 ms   165 ms   235 ms  165.238.3.57
  2    94 ms   216 ms   230 ms  165.238.3.49
  3    93 ms   199 ms   216 ms  12.122.253.197
  4    95 ms   307 ms   408 ms  12.123.12.233
  5   114 ms   287 ms   234 ms  192.205.31.70
  6   186 ms   298 ms   332 ms  208.178.255.74
  7   173 ms   328 ms   333 ms  208.178.255.94
  8   188 ms   323 ms   306 ms  208.48.118.118
  9    99 ms   229 ms   208 ms  208.50.169.62
 10   104 ms   279 ms   215 ms  206.132.254.37
 11   309 ms   375 ms   348 ms  208.178.103.62
 12   103 ms   238 ms   102 ms  204.71.202.160

Trace complete.

(The trace above was performed over a dialup modem connection. The times in ms would normally be much lower on a Cable Modem or DSL connection.)

For more information on TTL, see RFC 791.

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Why the System.ini Tweak Doesn't Work

The System.ini Network Card Tweak has its origins in a discussion thread entitled "Slow cable issue????"

The claim is that the tweak (IRQn=4096) improves network performance by allocating 4 megabytes of memory as a buffer for the IRQ (n) used by your network adapter. However:

While it doesn't help, the good news is that (like TTL) this setting doesn't hurt (assuming you don't screw up your SYSTEM.INI file) -- Windows just ignores settings that it doesn't recognize.

Note: This may have gotten its start as confusion over the real SYSTEM.INI settings COMnIrq and COMnBuffer, which are used to control serial port IRQ assignment and buffering (the latter of which can help serial port throughput). But these settings pertain only to the standard Microsoft serial port driver, not to network adapters.

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How to check your connection speed

Speed test sites on the Internet (e.g., dslreports.com Speed test) do not provide a reliable measurement of your local link speed. The reason is that a speed test from an arbitrary remote server will tell you about that particular route at that particular time under that particular server load, all things that can and do vary widely. (Worse, some speed test sites are so badly implemented that the results are pretty much meaningless.)

To accurately measure the speed of your local link, download a large file (at least one million bytes) from a local server under light load (e.g., Internet software from your ISP in the wee hours) and time how long it takes. When all the various overheads are taken into account, with optimum configuration of your computer (see "Increasing TCP Receive Window") your binary FTP download speed in bytes per second will be about 1/10 of the raw link speed in bits per second (e.g., about 150 KBytes/sec over 1500 Kbits/sec link; about 38 KBytes/sec over 384 Kbits/sec link).

If you are running Windows 98, you can continuously monitor the speed at which data is being sent and received over a network adapter (commonly used to connect a cable or DSL modem) by installing Network Monitor Agent, which is located in the Windows 98 CD directory \Tools\ResKit\NetAdmin\NetMon. Once installed, you will be able to add Network Monitor Performance items to the display in System Monitor. (Network Monitor Agent is also available for Windows 95 in the Windows 95 CD directory \Admin\NetTools\NetMon, and can also be downloaded from Microsoft by HTTP or FTP. The executable files in the Windows 95 download are exactly the same as the Windows 98 CD version, so the download should also work for Windows 98, notwithstanding the warning on the Microsoft web page. It may work for Windows Me as well.) For more information see Q200910 "How to Install Network Monitor in Windows 95/98".

If you are running Windows NT/2000/XP, you can continuously monitor the speed at which data is being sent and received over a network adapter (commonly used to connect a cable or DSL modem) with Performance Monitor. The Object to use is Network Interface. (For information on Instances, see Q154535 "Multiple Instances of Network Interface in Performance Monitor".)

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How to find out what's slowing you down

You've increased your TCP Receive Window, but what if you're still not getting the speed you expect? (1500 Kbits/sec ADSL service is capable of downloading at a bit more than 150 KBytes/sec.) It could just be a matter of a remote server with limited capacity. But it could also be a network under-capacity problem at your ISP (the result of overselling the available capacity to too many subscribers, an all too common problem). No matter what you may have heard or read, "the Internet" is not overloaded.

The usual symptoms of network under-capacity are high latency (the time it takes a packet to cross the network path from one end to the other) and packet loss (where transmitted data is literally lost because of insufficient network capacity). High latency has an adverse effect on interactive use; e.g., real-time gaming over the Internet. Packet loss has an adverse effect on just about everything.

The best way to pinpoint the source of a network problem is to use a standard TCP/IP network tool called 'traceroute', which measures both latency and packet loss at every network "hop" between you and your destination (remote server). Windows 95/98/Me/NT/2000/XP comes with a free version of traceroute called "tracert". It does a pretty good job, but the output can be hard to understand if you're not into networking. (See Microsoft's Q162326 "Using TRACERT to Troubleshoot TCP/IP Problems in Windows NT" [which also applies to Windows 95/98/Me])

One of the best traceroute alternatives is VisualRoute (shareware: $37.50) by Visualware, available for a variety of platforms, including Windows 95/98/Me/NT/2000/XP, Solaris, and Linux. A fully-functional 30-day demo is available for free download. It combines excellent ease of use with a high level of functionality, notably the ability to analyze the cause of network problems and display the results in English; e.g., (real example, emphasis added):

Analysis: Node 'ftp.cdrom.com' was found in 7 hops (TTL=249). But, problems starting at hop 6 in network "CRL Network Services, Inc" are causing IP packets to be dropped. Connections to HTTP port 80 are working.

Other good traceroute alternatives include:

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How the Upstream Cap can affect Downstream Speed

Although downstream speeds are usually high (typically in the range of 768 Kbps to 1.5 Mbps), consumer-grade Cable or DSL service often has an upstream cap (artificial limit) of 128 Kbps, which is only about 4 times faster than a V.90 (56K) dial-up modem (limited to about 31 Kbps upstream), and a fraction of the downstream speed.

What is not generally well-known is that the upstream cap can also affect the downstream speed -- if the upstream is saturated by uploading (e.g., sending a large PowerPoint file to the boss, or running a Napster or other public service), the downstream will drop to about the same speed. This is due to a weakness in the basic TCP Internet protocol, not Cable or DSL per se, and not the service provider.

Cable Internet is more vulnerable to this problem than DSL. Unlike DSL, where each subscriber has a dedicated connection to the head-end (DSLAM), the Cable Internet upstream path to the head-end (CMTS) is shared by all subscribers on a given cable segment. If that upstream gets saturated, which might be caused by only a relatively few subscribers, downstream speeds take a big drop for all subscribers on that segment.

As an illustrative example, consider a DOCSIS cable segment with 4 upstream channels per downstream channel, and 1000 subscribers (a recommended maximum).

The aggregate upstream capacity of 4 channels would be about 2.5 Mbps, as compared to downstream capacity of 27 Mbps. If the upstream saturates, the downstream rate will drop to about the same speed, a dramatic slowdown of about 90% (2.5 Mbps as compared to 27 Mbps).

Even with cable modems capped to 128 Kbps upstream, 2.5 Mbps upstream capacity can handle only 20 (2.5 Mbps / 128 Kbps) simultaneously active modems before saturation. That's generally not a problem if cable modem usage is typically (1) infrequent, (2) downstream [e.g., web surfing], and (3) interactive [e.g., fetch-use]. The system can break down if those conditions are not met.

This makes it easier to see why certain Cable Internet providers condemn continuous use of upstream (e.g., running a popular public service) as "abuse" -- each such subscriber consumes capacity normally allocated for 1000 / 20 = 50 subscribers. Worse, there's a threshold effect: If the upstream is running at (say) 80% of capacity with typical subscribers, it takes only 4 (out of 1000) heavy upstream users at 128 Kbps to drive the upstream into saturation, thereby slowing downstream to a crawl for all subscribers on that segment. (Exact numbers, of course, depend on actual channel numbers and speeds.)

For more information, see RFC 3449 "TCP Performance Implications of Network Asymmetry".

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Microsoft's TCP/IP retransmission bug

Microsoft has confirmed a TCP/IP retransmission bug in Windows 95, 98, and NT that can adversely affect upload (not download) throughput over "high-delay networks (for example, satellite links)." Standard Cable Modem or DSL service should not be affected by this bug; i.e., the fix is usually not needed. For more information see:

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Reduce DNS errors in Windows 2000/XP

Windows 2000 and Windows XP come with a "DNS Client" Service that automatically caches (temporarily saves) DNS addresses. This boosts performance by avoiding repetitive DNS lookups of the same address -- the results of a successful lookup (positive response) are saved and reused until the cache expires.

By default the DNS Client also caches negative responses (including the lack of any response from the DNS server). Unfortunately, that can prevent you from recovering from transient DNS errors for an extended period of time. If, for example, the DNS servers at your ISP are temporarily overloaded, or slow to respond due to network congestion, the DNS Client will cache the negative response. Until that cache entry expires, which can take several minutes, it won't even try to lookup that name again -- you'll just get an immediate error. That prevents you from quickly recovering from DNS errors by simply retrying, the recommended thing to do. This can lead to frustrating delays and seeming loss of connectivity problems.

The best way for the typical Internet user to deal with this issue is to disable negative caching, leaving positive caching intact. (Completely disabling the DNS Client is like throwing the baby out with the bathwater because you would then lose the benefits of positive caching.) Negative caching can be disabled by adding three Registry Values (NegativeCacheTime, NegativeSOACacheTime, and NetFailureCacheTime, all not normally present), setting them to zero. Since manual editing of the Registry is a tricky and risky business, I've provided a simple Registry script to do the job. (Click the link to start the download; save the script to your desktop; and then double-click on it to run it. When you get the "Are you sure you want to add the information..." dialog box, click Yes. The script can then be discarded.)

There is no real downside to making these changes -- just delay if you make repeated tries to an invalid Internet name. (Nevertheless, please note that you do this at your own risk, and that it's always a good idea to back up your Registry before making any change.)

To go back to Windows default behavior, simply remove the three Registry Values described above. Since manual editing of the Registry is a tricky and risky business, I've provided a simple INF script to do the removal. (Click the link to start the download; save the INF file to your desktop; right-click on it, and then choose Install to run it. The INF file can then be discarded.)

For a more complete discussion and explanation of this issue, see "Broadband Tip: How to keep DNS Errors from slowing you down!"

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Security on Cable Modem or DSL for Microsoft Windows

Security on a full-time Cable Modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular. Wireless networking also presents security risks -- see "Security of the WEP algorithm".

If you are running Windows 95/98/Me, at a minimum you should make sure that the built in capability for File and Print Sharing can't be used against you over the Internet using one of the following methods:

Case A: Disable File and Print Sharing
You don't want to share files or printers on a local area network. (Your computer and workgroup names will still be visible, but that does not actually make you less secure.)
  1. Open Control Panel - Network.
  2. Disable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. UN-check the two options for files and printer(s).
    3. Click OK twice to close the Network windows.
  3. Restart your computer if prompted to do so.
  4. Close Control Panel.
Case B: Disable NetBIOS over TCP/IP
You want to conceal your computer and workgroup names from the Internet (even though that does not actually make you more secure), or you do want to share files or printers on a local area network using (only) NetBEUI (which is safe from the Internet, unlike TCP/IP) for File and Print Sharing.
Note:
Disabling NetBIOS over TCP/IP may cause connection problems with some Internet Service Providers. If you experience problems, or simply want to avoid any problems, use Case A, Case C, or  Case D, which are equally secure.
  1. Open Control Panel - Network.
  2. If NetBEUI is not installed in the Configuration list:
    1. Click Add.
    2. Select Protocol.
    3. Click Add.
    4. Select Microsoft as the Manufacturer, and then NetBEUI as the Network Protocol.
    5. Click OK twice to close the Network windows.
    6. Restart your computer if prompted to do so, and then reopen Network.
  3. If you do want to share files or printers on a local area network, enable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. Check (enable) the desired options for files and/or printer(s).
    3. Click OK twice to close the Network windows.
  4. Restart your computer if prompted to do so, and then reopen Network.
  5. Unless you normally logon to Microsoft Networks (e.g., Windows NT/2000/XP servers), Primary Network Logon should be set to Windows Logon.
  6. UN-bind TCP/IP from Microsoft Networking for all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the Bindings tab.
    3. UN-check the option File and Printer Sharing for Microsoft Networks
    4. UN-check the option Client for Microsoft Networks.
    5. Click OK twice to close the Network windows. If you get the message "You have not selected any drivers to bind with. Would you like to select one now?", click No.
  7. Restart your computer if prompted to do so, and then reopen Network.
  8. Make sure that NetBIOS is not enabled on all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the NetBIOS tab.
    3. UN-check (if checked) the option I want to enable NetBIOS over TCP/IP.
    4. Click OK twice to close the Network windows.
  9. Restart your computer if prompted to do so.
  10. Close Control Panel.
Case C: Unbind TCP/IP from File and Printer Sharing
You do want to share files or printers on a local area network using (only) NetBEUI (which is safe from the Internet, unlike TCP/IP) for File and Print Sharing. (Your computer and workgroup names will still be visible, but that does not actually make you less secure.)
  1. Open Control Panel - Network.
  2. If NetBEUI is not installed in the Configuration list:
    1. Click Add.
    2. Select Protocol.
    3. Click Add.
    4. Select Microsoft as the Manufacturer, and then NetBEUI as the Network Protocol.
    5. Click OK twice to close the Network windows.
    6. Restart your computer if prompted to do so, and then reopen Network.
  3. If you do want to share files or printers on a local area network, enable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. Check (enable) the desired options for files and/or printer(s).
    3. Click OK twice to close the Network windows.
  4. Restart your computer if prompted to do so, and then reopen Network.
  5. Unless you normally logon to Microsoft Networks (e.g., Windows NT/2000/XP servers), Primary Network Logon should be set to Windows Logon.
  6. UN-bind TCP/IP from File and Printer Sharing for Microsoft Networks for all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the Bindings tab.
    3. UN-check the option File and Printer Sharing for Microsoft Networks.
    4. Check (enable) the option Client for Microsoft Networks.
    5. Click OK twice to close the Network windows. If you get the message "You have not selected any drivers to bind with. Would you like to select one now?", click No.
  7. Restart your computer if prompted to do so.
  8. Close Control Panel.
Case D: Set a Scope ID for File and Printer Sharing over TCP/IP
You do want to share files or printers on a local area network or over the Internet using TCP/IP for File and Print Sharing. (Your computer and workgroup names will not be visible except to other computers with the same Scope ID.)
     See "Increasing NetBIOS Security with Scope ID".

If you are running Windows NT/2000/XP, security is considerably more complex than for Windows 95/98/Me. Start with:

For more information on the real risks of Microsoft Networking, see "File and Printer Sharing (NetBIOS) Fact and Fiction".

For greater security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

    »   AnalogX PortBlocker (free, port blocking only)
    »   BlackICE Defender Shopping on-line tips (click) buy.com
    »   ConSeal PC Firewall (Recommended)
    »   eSafe Protect Desktop
    »   Internet Guard Dog Shopping on-line tips (click) buy.com
    »   Internet Firewall 98 For Personal Computers
    »   Internet Firewall 2000 For Personal Computers
    »   LockDown 2000 (trojan scanning)
    »   McAfee.com Personal Firewall (MPF) (Recommended)
(formerly ConSeal Private Desktop)
Shopping on-line tips (click) buy.com
    »   NetWatcher 2000
    »   Norton Internet Security
(partially derived from WRQ AtGuard)
Shopping on-line tips (click) buy.com
    »   Norton Personal Firewall
(partially derived from WRQ AtGuard)
Shopping on-line tips (click) buy.com
    »   PC Viper
    »   PGP Desktop Security Shopping on-line tips (click) buy.com
    »   SOS Best Defense
    »   SPHINX Personal Firewall
    »   Sygate Personal Firewall (free for personal use)
    »   Tiny Personal Firewall (free for personal/home use; ICSA-certified technology; recommended)
    »   WinRoute Pro
    »   WRQ AtGuard
    »   ZoneAlarm (free; recommended for those on a budget)

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls (SOHO Routers)".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

Content Filtering

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering:

    »  

Hardware

    »  SonicWALL + Content Filter List Subscription (Recommended)

Shopping on-line tips (click) buy.com
    »  

Software

    »  Cyber Patrol
    »  Cyber Sentinel
    »  Cyber Sitter

    »  Net Nanny

Shopping on-line tips (click) buy.com
    »  SOS Kidproof

[Jump to Contents]


Security on Cable Modem or DSL for OS/2

Security on a full-time Cable Modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular. Wireless networking also presents security risks -- see "Security of the WEP algorithm".

For real security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls (SOHO Routers)".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software or hardware (e.g., SonicWALL).

[Jump to Contents]


Security on Cable Modem or DSL for Apple Macintosh

Security on a full-time Cable Modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular. Wireless networking also presents security risks -- see "Security of the WEP algorithm".

For real security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

    »   DoorStop
    »   NetBarrier Shopping on-line tips (click)

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls (SOHO Routers)".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

Content Filtering

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering:

    »  

Hardware

    »  SonicWALL + Content Filter List Subscription (Recommended)

Shopping on-line tips (click) buy.com
    »  

Software

    »  Cyber Patrol

[Jump to Contents]


Hardware Firewalls (SOHO Routers)

Security on a full-time Cable Modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular. Wireless networking also presents security risks -- see "Security of the WEP algorithm".

You get the best possible external protection by using a separate standalone (hardware) firewall. (Software firewalls may still provide better protection against internal attacks; e.g., trojans, spyware.) Many of these products also include NAT (network address translation, see RFC 1631) for sharing a single Cable Modem or DSL connection (see "How to run multiple computers on Cable Modem or DSL"):

    »   Addtron ADR-E200P (inc. dial-in port, printer server) Shopping on-line tips (click) buy.com
Allied Telesyn
    »  AT-AR220E Router
    »  AT-AR320 Router (inc. secure dial-in ports) Shopping on-line tips (click) buy.com
    »   BeadleNet SOHO2000
    »   D-Link DI-701 Residential Gateway Shopping on-line tips (click) buy.com
    »   Farallon NetLINE Broadband Gateway Shopping on-line tips (click) buy.com
    »   Kingston KNR7TXD Internet Access Router
Linksys
    »  BEFSR11 EtherFast 1-Port Cable/DSL Router Shopping on-line tips (click) buy.com
    »  BEFSR41 EtherFast 4-Port Cable/DSL Router Shopping on-line tips (click) buy.com
    »  BEFSR81 EtherFast 8-Port Cable/DSL Router (QoS) Shopping on-line tips (click) buy.com
    »   Macsense XRouter (NAT only* Shopping on-line tips (click) buy.com
MaxGate
    »  Ugate-Plus Shopping on-line tips (click) buy.com
    »  Ugate-3000 Shopping on-line tips (click) buy.com
    »  Ugate-3200 Shopping on-line tips (click) buy.com
    »   Multi-Tech ProxyServer
NETGEAR
    »  Gateway Router RT311 (Recommended) Shopping on-line tips (click) buy.com
    »   Cable/DSL Firewall Router FR314 (stateful inspection; IPsec VPN pass-through) (Recommended) Shopping on-line tips (click) buy.com
    »  Cable/DSL Router RT314 (Recommended) Shopping on-line tips (click) buy.com
    »   Netopia Routers
NexLand
    »  ISB2LAN (NAT only*; multi-session IPsec VPN pass-through)
    »  ISB SOHO (NAT only*; single-session IPsec VPN pass-through)
    »  ISB Processional Series (wide range of models)
    »   SMC Barricade (inc. printer server) Shopping on-line tips (click)
    »   SonicWALL (stateful inspection; ICSA Certified; supports IPsec VPN) (Recommended) Shopping on-line tips (click) buy.com
    »   3Com OfficeConnect Internet firewall (based on SonicWALL) Shopping on-line tips (click)
    »   WatchGuard SOHO   Shopping on-line tips (click) buy.com
    »   WebRamp 700s (private label SonicWALL)
ZyXEL
    »  Prestige 310 Shopping on-line tips (click) buy.com
    »  Prestige 312 (stateful inspection; ICSA Certified) (Recommended) Shopping on-line tips (click) buy.com
    »  Prestige 314 Shopping on-line tips (click) buy.com
    »  Prestige 316 (wireless)
    »  ZyWALL 10 (stateful inspection) (Recommended)

* Products based only on NAT are less effective than true firewalls.

See also "ADSL Modem Guide (DMT issue 2)" for products that include packet filtering or firewall.

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software (e.g., NetNanny) or hardware (e.g., SonicWALL).

If you are a "power" user, you can build your own low-cost firewall with:

    »   Linux e.g.,
    »  Astaro Security Linux (free for private home use)
    »  Coyote Linux (variant of Linux Router Project)
    »  FirePlug EDGE Project
    »  Freesco (successor to Ballantain)
    »  Linux Router Project
    »  NetBSD/i386 Firewall
    »  NetMAX (not free) Shopping on-line tips (click) buy.com
    »  ShareTheNet (not free)
    »   FreeBSD
    »   GNATBox (Recommended)
    »   IPRoute
    »   OpenBSD

[Jump to Contents]


Check Your Security

Even if you are scrupulous about security precautions, you still might inadvertently overlook or even create a security risk. You can get good insurance (and peace of mind) by having your system checked. To be thorough and accurate, such checks should be performed from outside your system by a trusted resource using proper tools. Contents:

Services

Recommended websites that offer checking services:

Not recommended websites that offer checking services:

For a review of checking services, see ZDNet "Online Security Services".

Ports (and what they mean)

Resources (information & tools)

(HackerWhacker is a claimed trademark of HackerWhacker. "Shields UP!" is a claimed trademark of Gibson Research Corporation. CERT is a registered service mark of Carnegie Mellon University.)

[Jump to Contents]


Privacy on the Internet

Although the Internet can be an incredibly valuable resource, it can also be used against your interests, often without your knowledge or consent. Businesses (and other organizations) now routinely use the Internet to gather and compile personal information profiles. All too often these profiles are traded between businesses and aggregated into even more comprehensive profiles, to which just about anyone can get access, even those with bad intentions. In addition to basic information, these profiles can include employment information, financial information (e.g., bank accounts, credit card numbers, brokerage accounts), medical information, personal habits (e.g., what you buy, what you read, what you do), and much more. Here's how this works:

[Jump to Contents]


What is PPPoE?

PPPoE stands for Point-to-Point Protocol over Ethernet, a newer alternative to traditional bridging and routing for high-speed Internet connections. Although not an Internet standard, PPPoE is described in the Informational RFC 2516.

Some providers are touting PPPoE ("dynamic IP") as safer than bridge/routed service, but this is a dangerous misconception -- PPPoE is not significantly safer.

PPPoE currently requires either:

Special PPPoE Software:

Hardware with PPPoE support:

Allied Data Technologies
    »  CopperJet 800/E
    »  CopperJet 800/USB
    »   Cisco Routers
    »   D-Link DI-701 Residential Gateway Shopping on-line tips (click) buy.com
Linksys
    »  BEFSR11 EtherFast 1-Port Cable/DSL Router Shopping on-line tips (click) buy.com
    »  BEFSR41 EtherFast 4-Port Cable/DSL Router Shopping on-line tips (click) buy.com
    »  BEFSR81 EtherFast 8-Port Cable/DSL Router Shopping on-line tips (click) buy.com
    »   Macsense XRouter (NAT only* Shopping on-line tips (click) buy.com
    »   MaxGate
    »  Ugate-Plus Shopping on-line tips (click) buy.com
    »  Ugate-3000 Shopping on-line tips (click) buy.com
    »  Ugate-3200 Shopping on-line tips (click) buy.com
NETGEAR
    »  Gateway Router RT311 (Recommended) Shopping on-line tips (click) buy.com
    »   Cable/DSL Firewall Router FR314 (stateful inspection; IPsec VPN pass-through) (Recommended) Shopping on-line tips (click) buy.com
    »  Cable/DSL Router RT314 (Recommended) Shopping on-line tips (click) buy.com
    »   Netopia Routers
NexLand
    »   ISB2LAN (NAT only*; multi-session IPsec VPN pass-through)
    »  ISB SOHO (NAT only*; single-session IPsec VPN pass-through)
    »  ISB Processional Series (wide range of models)
    »   SMC Barricade Shopping on-line tips (click)
    »   SonicWALL (supports IPsec VPN) (Recommended) Shopping on-line tips (click) buy.com
ZyXEL
    »  Prestige 310 Shopping on-line tips (click) buy.com
    »  Prestige 312 Shopping on-line tips (click) buy.com
    »  Prestige 314 Shopping on-line tips (click) buy.com
    »  Prestige 316 (wireless)
    »  Prestige 641 Shopping on-line tips (click) buy.com
    »  Prestige 642

Important Notes:

DHCP (long hangs)
If you are running PPPoE software on Windows, and your computer seems to "hang" at startup and/or at times while you are accessing the Internet, the cause may be DHCP timeout. The fix is to set a private IP address (e.g., 192.168.0.1, with a Subnet Mask of 255.255.255.0) Under Windows 95/98/Me, go to Control Panel - Network - TCP/IP pointing to something other than Dial-Up Adapter -  Properties - IP Address.
Internet Explorer "No Connection" Problem
If Internet Explorer 5.0 keeps reporting that there is "No Connection" but recovers with "Try Again" try installing Service Pack 1, or upgrade to Internet Explorer 5.5 (or above).
MTU (access problems)
Certain PPPoE implementations do not work well with an MTU setting of 1500 (the Microsoft Windows default). The work-around is to manually set MTU to a lower value in the range of 1400-1492. This problem is reportedly fixed in Enternet 1.31 for Windows and 5.09b for Macintosh.
Staying Connected
To keep Windows NT/2000/XP connected after logging off, see Q158909 "How to Keep RAS Connections Active After Logging Off".
Win98SE NDIS Problem
If you are running PPPoE software on Windows 98 Second Edition, see Q243199 "Windows 98 Second Edition Problems with NDIS Intermediate Drivers"

For vendor/provider perspectives on PPPoE, see:

For subscriber perspectives on PPPoE (particularly problems resulting from premature deployment), see:

[Jump to Contents]


What is PPPoA?

PPPoA stands for Point-to-Point Protocol over ATM (more precisely ATM Adaptation Layer 5, or AAL5), another newer alternative to traditional bridging and routing for high-speed Internet connections. Unlike PPPoE, PPPoA is an Internet standard as described in RFC 2364.

Some providers are touting PPPoA ("dynamic IP") as safer than bridge/routed service, but this is a dangerous misconception -- PPPoA is not significantly safer.

PPPoA requires hardware with PPPoA support: Linux/BSD support for PPPoA:

See also:

[Jump to Contents]


Sharing Cable Modem or DSL on multiple computers

See Navas Cable Modem/DSL Sharing GuideTM

Windows 98 Second Edition and Windows 2000/XP include Internet Connection Sharing (ICS), which provides basic functionality for sharing a single Internet connection on a small peer-to-peer network. The drawback is that such sharing only works when the sharing computer ("gateway") is up and running, which can be inconvenient. Information on using ICS can be found in:

A third-party alternative that gets high marks for compatibility (e.g., with PPPoE) and ease of use is All Aboard! from InterNetShare.com. (Recommended)

For Apple Macintosh, similar sharing functionality is available in:

Other alternatives for sharing include:

Standard cabled networking hardware:

    »   Intel Shopping on-line tips (click) buy.com
    »   Kingston Shopping on-line tips (click) buy.com
    »   NETGEAR (Recommended) Shopping on-line tips (click) buy.com
    »  FA310TX 10/100 Fast Ethernet PCI Adapter Shopping on-line tips (click) buy.com
    »  DS106 10/100 Mbps Dual Speed Hub (6 port) Shopping on-line tips (click) buy.com
    »  DB104 10/100 Mbps Ethernet Kit Shopping on-line tips (click) buy.com
    »   3Com Shopping on-line tips (click) buy.com
    »   Good place for network cable: Home Depot (yes, Home Depot)

Networking without having to run network cables:

Wired phoneline networking:
    »  D-Link Home Phoneline Network Shopping on-line tips (click) buy.com
    »  Diamond HomeFree Shopping on-line tips (click) buy.com
    »  Farallon HomeLINE (Recommended) Shopping on-line tips (click) buy.com
    »  Intel AnyPoint (1 Mbps or 10 Mbps) Shopping on-line tips (click) buy.com
    »  Linksys HomeLink Shopping on-line tips (click) buy.com
    »  NETGEAR Phoneline10X Shopping on-line tips (click) buy.com
    »  3Com HomeConnect Shopping on-line tips (click)
    »  Zoom HomeLAN
Wired powerline networking:
    »  Intelogis PassPort Shopping on-line tips (click)
Wireless networking* (1-2 Mbps):
    »  Acer WarpLink Shopping on-line tips (click) buy.com
    »  Diamond HomeFree Shopping on-line tips (click) buy.com
    »  Intel AnyPoint Shopping on-line tips (click) buy.com
    »  Proxim Symphony Shopping on-line tips (click) buy.com
    »  SOHOware CableFREE Shopping on-line tips (click) buy.com
    »  WebGear Aviator
Wireless networking* (10 Mbps):
    »  RadioLAN
Wireless networking* (11 Mbps IEEE802.11b DSSS; recommended):
    »  Addtron Technology Shopping on-line tips (click) buy.com
    »  Buffalo Technology (Recommended) Shopping on-line tips (click)
    »  D-Link Wireless Shopping on-line tips (click) buy.com
    »  Farallon SkyLINE Shopping on-line tips (click) buy.com
    »  Linksys Instant Wireless Shopping on-line tips (click) buy.com
    »  Nexland ISB WaveBase
    »  ORiNOCO Shopping on-line tips (click)
    »  SMC Shopping on-line tips (click) buy.com
    »  Zoom ZoomAir Shopping on-line tips (click)
Standards and Technology:

* Wireless networking presents security risks -- see "Security of the WEP algorithm".

[Jump to Contents]


Low-cost server for your small network

In addition to typical server tasks (e.g., file storage, printing), a dedicated network server can also be used for sharing a Cable Modem or DSL service (e.g., network address translation, proxy) and to provide security (e.g., firewall, filtering), with the advantage that such sharing does not depend on any other computer. (See "How to run multiple computers on Cable Modem or DSL" and "Security on Cable Modem or DSL") It can also make it possible to have a more complete Internet presence by providing such services as DNS (domain name service for a custom domain), email, HTTP (World Wide Web pages), FTP, and VPN (virtual private networking, providing secure access to your local network from anywhere on the Internet -- see "VPN/PPTP over Cable Modem or DSL"). Options:

  1. BSD
  2. Linux
  3. Solaris
  4. Windows NT/2000/XP

Option 1: BSD

BSD variants provide a wealth of standard Internet tools, and are available by download and on CD at little or no cost (e.g., CheapBytes). BSD is generally regarded as being more solid than Linux. Although peer support is available on the Internet, setting up and administering BSD can be difficult for those without UNIX experience. Complete BSD distributions include:

Option 2: Linux

Linux also provides a wealth of standard Internet tools, and is available by download and on CD at little or no cost (e.g., CheapBytes). Linux is generally regarded as having a more complete feature set than BSD. Although peer support is available on the Internet, setting up and administering Linux can be difficult for those without UNIX experience. Complete Linux distributions include:

Option 3: Solaris

Solaris from Sun Microsystems is the operating system that largely powers the Internet, excelling in both power and reliability. Sun now offers two ways to get Solaris at low cost (for media and shipping):

Setting up and administering Solaris can be difficult for those without UNIX experience.

Option 4: Windows NT/2000/XP

Microsoft used to offer a Small Business Server 4.5 Guided Tour Evaluation Kit for only US$20 that was fully functional with no time limitation, albeit limited to 6 client access licenses. However, that offer was replaced with the Small Business Server 2000 Evaluation Kit, which is time-limited to 120 days, leaving Windows unaffordable as a home/SOHO server.

Resources (not checked for accuracy):

[Jump to Contents]


How to run services (servers) on dynamic IP

Dynamic IP means that your Internet (IP) address changes from time to time, sometimes every few hours, sometimes at much longer intervals. (A static IP address remains the same indefinitely.) Running services (servers) on dynamic IP is not normally possible because the current address is not known to outside world. The solution is to use a "Dynamic DNS" service that tracks changes in your IP address. Dynamic DNS providers include:

Notes:

[Jump to Contents]


How to share your files with NetBIOS over Cable Modem or DSL

UPDATE (10/10/2000): Microsoft Windows 95/98/Me Share Level Password Vulnerability (bugtraq 1780) makes NetBIOS (Microsoft Networking) Share Level passwords easy to defeat if Scope ID is not used (see "Increasing NetBIOS Security with Scope ID"). If NetBIOS is not disabled (see "Security on Cable Modem or DSL"), then installing the Microsoft patch is strongly recommended!

Windows (95/98/Me/NT/2000/XP) includes the capability of sharing files and printers over a network connection by means of NetBIOS (Microsoft Networking). With "NetBIOS over TCP/IP" such sharing can take place over the Internet. Scope ID should be used to enhance NetBIOS security -- see "Increasing NetBIOS Security with Scope ID". Note that NetBIOS provides authentication, but not encryption; for greater security, use VPN/PPTP. (See "VPN/PPTP over Cable Modem or DSL")

Caveat: Some Internet Service Provider (ISP) filter (block) ports used for NetBIOS because of hysteria over NetBIOS (see "File and Printer Sharing (NetBIOS) Fact and Fiction") and/or genuine concern for subscribers that might inadvertently expose themselves to NetBIOS security risks (see "Security on Cable Modem or DSL"). In such cases it will not be possible to use NetBIOS over the Internet unless you can persuade the ISP to remove the filter (block) on your particular Cable Modem or DSL connection.

For more information on using NetBIOS sharing over the Internet, see:

Remote Control

An excellent way to remote control your own computer over Cable Modem or DSL is with free Virtual Network Computing (VNC) software. (Recommended)

[Jump to Contents]


VPN/PPTP over Cable Modem or DSL

VPN (Virtual Private Networking) is a means of creating secure connections over the Internet between two computers and/or local area networks (LAN's). Microsoft includes a form of VPN called PPTP (Point-to-Point Tunneling Protocol) in Windows NT/2000/XP, as well as PPTP clients for/in Windows 95/98/Me.

The most robust and secure form of VPN is generally considered to be IPsec (described in Standards Track RFC 2401).

VPN resources:

[Jump to Contents]


How to use cable/DSL and dialup at the same time

Suppose you need to use Windows 95/98/Me Dial-Up Networking (DUN) to connect to your employer's network. The usual problem is that you lose the use of your Cable Modem or DSL connection during the DUN connection. The reason that happens is that DUN automatically gets higher routing priority than your Cable Modem or DSL connection because Windows 95/98/Me can only have one default route. In other words, your Cable Modem or DSL connection is still alive, but Windows 95/98/Me won't use it.

The solution to this problem is a two-step process:

1.  Prevent DUN from getting higher routing priority.

  1. Set up a DUN Connection ("connectoid") for this particular purpose.
  2. Right-click on this DUN connectoid and select Properties.
  3. Click on the Server Types tab.
  4. Un-check any unnecessary network protocols (e.g., NetBEUI, IPX/SPX).
  5. Un-check Log on to network unless it's actually needed (e.g., for your employer's network).
  6. Click on TCP/IP Settings.
  7. Un-check Use default gateway on remote network. (This is the critical item.)
  8. Click OK to close all the dialog boxes.

Now when you connect with this particular DUN connectoid, your Cable Modem or DSL connection will still work, but the DUN connection won't. To get the DUN connection working, proceed with the second step below after you have connected.

2.  Add manual route(s) for your DUN connection.

  1. Connect with the DUN connectoid created in the first step above.
  2. Run the command "WINIPCFG".
  3. Select "PPP Adapter" in the drop-down list.
  4. Note the IP Address. (Assume it's 206.170.4.214 for illustration purposes.)
  5. Close WINIPCFG.
  6. Suppose the IP address you want to reach through the DUN connection is 207.200.75.200 (netscape.com). To manually add that route through your PPP Adapter (206.170.4.214 in our example), run the command:

    Syntax:

    ROUTE  ADD   destination     gateway

    Example:

    ROUTE  ADD  207.200.75.200  206.170.4.214

  7. Now traffic to the destination you just added (207.200.75.200 in this example) will go out through DUN, and traffic to the rest of the Internet will still go out through your Cable Modem or DSL connection.
  8. You can add multiple manual routes. You can also use trailing 0 values with a corresponding MASK as destination wildcards; e.g.,
    Destination Mask Means all destinations starting with Example
    207.200.75.0 255.255.255.0 207.200.75. ROUTE ADD 207.200.75.0 MASK 255.255.255.0 206.170.4.214
    207.200.0.0 255.255.0.0 207.200. ROUTE ADD 207.200.0.0 MASK 255.255.0.0 206.170.4.214
  9. When you disconnect DUN your manual routes will be lost, and the IP address of your PPP Adapter will probably change from connection to connection, so this step must be repeated after each connection. 

[Jump to Contents]


How to "bond" multiple cable/DSL and/or dial-up connections

Using multiple Cable Modem, DSL, and/or dial-up modem connections together for increased speed normally requires either special bonding support from the Internet Service Provider (ISP) or an expensive, sophisticated load-balancing router. Affordable alternatives:

Note: This author has no connection to these companies and has not tested these products.

[Jump to Contents]


How to Un-Cap a Cable or DSL Modem

"Cap" is a reference to an artificial limit on downstream and/or upstream speeds. Such caps are common on consumer-grade service. "Un-capping" is thus an attempt to remove such limits (and thereby increase speed).

However, un-capping is an urban legend (or hoax, take your pick) -- subscribers cannot un-cap cable or DSL modems:

(Note that if you did somehow find a way to do it, that might be construed as theft of service, with unpleasant consequences.)

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How to send a fax over Cable Modem or DSL

Unlike most dial-up modems, a cable or DSL modem is not capable of connecting to fax machines, so cannot send or receive faxes directly. However, it is possible to send and receive faxes over the Internet by using an Internet fax service. For information on such services, some of which are free, see:

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Third-party email service

What do you do if your ISP has poor email service, or if you anticipate someday switching to a different ISP? Consider a third-party email service, some of which are free. Many people do not realize that they don't have to use services provided by the ISP. Third-party email services are accessible by a web browser (web-based) and/or an email program (POP3/IMAP4) -- be sure to find out what you will be getting. Third-party email services include:

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Third-party news (Usenet) service

What do you do if your ISP has poor news service? Consider a third-party news service. Many people do not realize that they don't have to use services provided by the ISP. Third-party news services are accessible by a web browser (web-based) and/or a news program (NNTP) -- be sure to find out what you will be getting. Commercial third-party news services include:

See also

Public (free) news services

Open public news servers tend to be few and far between, and to disappear without warning, because they can easily be overwhelmed by freeloaders, and abused by spammers. Here are some ways to find one:

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Which is better: Cable Modem or DSL?

It all depends on the particular providers, the particular geographic area, and your specific requirements. There is no hard and fast rule. Either one can be good, mediocre, or poor.

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Which is better: Ethernet or USB or PCI?

External modems usually come with either an Ethernet or a USB interface. Another alternative is an internal modem, which usually comes with a PCI connector. Each interface has certain advantages and disadvantages:

Ethernet

  • Pro
    • Stable and mature technology
    • Widely supported
    • Efficient
    • Flexible
    • Host adapters are inexpensive
  • Best for: All-around use
  • Con
    • Requires an Ethernet port/adapter to connect
    • Ethernet cabling can be confusing
USB
  • Pro
    • Standard on most modern computers
    • Low cost
  • Best for: Notebook computers
  • Con
    • Requires special drivers
    • Operation can be unreliable/problematic
    • Won't work with a SOHO router or network bridge
    • Poor efficiency, puts considerable load on the host
PCI
  • Pro
    • Low cost
    • Less clutter
  • Best for: Limited requirements
  • Con
    • Must be installed in computer in open PCI slot
    • Requires special drivers
    • Operating system support may not be available
    • Won't work with a SOHO router or network bridge

Bottom line: Ethernet is preferred unless there is a compelling reason to use some other type. USB is better suited for low-speed devices (e.g., mice) than for Cable Modem or DSL.

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Buy (rather than rent) a Cable Modem

Cable Modems fall into two general categories: proprietary and DOCSIS standard. Buying a proprietary Cable Modem is probably unwise (due to obsolescence and lack of compatibility) and difficult (since such products are not normally sold at retail). A consumer market for DOCSIS standard modems is developing, but you should only purchase a DOCSIS Cable Modem if your cable supplier supports the DOCSIS standard. For more information see:
 
    »   Cable Modems:
    »  Cable/xDSL Modem Gallery
    »  DOCSIS Cable Modem Gallery
    »  DOCSIS Cable Modem Vendors
    »   Where to buy:
    »  Best Data Smart One Cable Modem CMI110 (Internal) Shopping on-line tips (click) PriceGrabber.com
    »  Best Data Smart One Cable Modem CMX110 (External) Shopping on-line tips (click) CNET Prices
    »  3Com HomeConnect Cable Modem External (Ethernet+USB) Shopping on-line tips (click)
    »  ELSA MicroLink Cable Modem Shopping on-line tips (click) buy.com
    »  SURFboard SB2100 Cable Modem (Ethernet) (Motorola store)
    »  SURFboard SB3100 Cable Modem (Ethernet) (Motorola store) Shopping on-line tips (click) BiggerBytes
    »  SURFboard SB4000 Cable Modem (Internal) (Motorola store)
    »  SURFboard SB4100 Cable Modem (Ethernet+USB) (Motorola store) Shopping on-line tips (click) BiggerBytes
    »  Toshiba PCX-1100 Cable Modem (Ethernet) (Toshiba Store) Shopping on-line tips (click) Components Direct
    »  Toshiba PCX-1100U Cable Modem (USB)
    »  ZyXEL Prestige 941 Cable Modem Bridge/Router (Ethernet, SUA/NAT) Shopping on-line tips (click) ZyXEL Shop
    »  ZyXEL Prestige 942 DOCSIS Cable Modem Bridge (USB, SUA/NAT) Shopping on-line tips (click) ZyXEL Shop
    »   ZyXEL Prestige 944 DOCSIS Cable Modem Bridge/Router (Ethernet, Hub, SUA/NAT) Shopping on-line tips (click) ZyXEL Shop
    »   ZyXEL Prestige 961 Euro DOCSIS Cable Modem Bridge/Router (Euro, Ethernet, SUA/NAT) Shopping on-line tips (click) ZyXEL Shop

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Remove @Home proxy settings

Proxy servers are used by some ISP's to provide faster web access to subscribers at lower cost (since it's usually faster to access a local proxy than to access a remote server over the Internet, and since local traffic is much less costly for the ISP than Internet traffic). In general, proxy servers work well, but there can be cases where they cause problems (e.g., if they get overloaded).

The software distributed by @Home normally autoloads proxy settings, preventing bypass of the proxy. To remove the autoload of the @Home proxy settings under Windows: 

  1. Click Start » Run.
  2. Type "REGSVR32 /U AHIEHELP.DLL" (no quotes).
  3. Press <Enter>.

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Other Cable Modem Resources

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What is "Interleaved Mode?"

DMT ADSL (one of the two principal forms of ADSL, the other being CAP) can commonly be configured to operate in two different modes:
Interleaved Mode
Data is spread out during ADSL transmission. This improves the ability to correct errors due to noise pulses, and can thus make the connection more reliable. However, interleaving increases latency (delay). The amount of interleaving determines the amount of spread and hence the amount of latency. Interleaved Mode is required with G.lite (because more adverse line conditions are expected).
Fast (or FastPath) Mode
Lower latency than Interleaved Mode, but more vulnerable to errors due to noise pulses.

If your "ping" time to the closest/first node (often called a "gateway") is less than 30 ms, your DMT ADSL is probably configured for Fast Mode. Otherwise, unless the physical distance to that closest/first node is unusually far, your DMT ADSL is probably configured for Interleaved Mode. (See "How to find out what's slowing you down")

For most uses the difference in latency is usually not significant, and the increase in reliability can be useful or even vital. However, the difference in latency can be important for fans of real-time gaming over the Internet. If you fall into that category; are on DMT and aren't on G.lite; aren't unusually far from the closest node; and experience latency to the closest node of more than about 30 ms, you may be able to persuade your provider to switch you from Interleaved Mode to Fast Mode if such a switch is possible. (It may not be.)

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DSL over DLC (Digital Loop Carrier)

Did your provider tell you that you didn't quality for DSL service because your phone line is served by DLC (aka SLC, Pair Gain, multiplexor)? For a discussion of issues and resolutions related to DSL over DLC, see "Extending Asymmetric Digital Subscriber Line (ADSL) Services to Remote Digital Loop Carrier (DLC) Locations Tutorial" (Web ProForum).

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How to fix phone problems caused by ADSL

One of the advantages of ADSL service is that it can provide both voice and data over the same telephone line by means of "micro-filters" (with G.lite) or a "splitter" (with full rate ADSL) that separate voice (as well as dialup modem and fax) signals from ADSL data signals; e.g.,
ADSL diagram
However, enough ADSL signal can "leak" past some splitters to adversely affect some voice telephones. (The splitter originally used by Pacific Bell was a notable offender. See note below.) The common symptoms are: ADSL suppliers have a bad habit of blaming the problem on your telephone, rather than the splitter. You can insist on a proper splitter, but that can be a frustrating, time consuming hassle. Fortunately, you may well be able to fix the problem yourself with an inexpensive filter that you install next to (or otherwise upstream of) the affected phone(s). Excelsus Technologies (800-457-0967 or 760-753-9108) is a good source of this kind of filter, which it calls the "Z-BLOCKER". In the USA, use the "Z-200 W / USA WALL-PHONE" if you have a wall phone; otherwise use the "Z-200 SM / USA & EUROPE", preferably located as far from the phone as possible.
ADSL diagram with filter
Notes: Where to buy a splitter:

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DSL problems caused by your own lighting 

Some DSL modems (e.g., Alcatel 1000) are overly sensitive to RFI (radio frequency interference). Lighting dimmer switches and/or electronic (non-magnetic) power supplies for halogen lighting are a common source of such interference. The result can be a degradation of DSL performance or even a complete loss of DSL sync, even when the source of the interference is not in close proximity to the DSL modem (because the interference can be not only radiated, but also conducted through building wiring). Interference is even possible when such switches and/or lights appear to be off, since some still generate interference even when turned off.

If you experience DSL problems, particularly when those problems seem to be worse at certain times of the day, you can check for this possible cause by completely disconnecting all lighting dimmer switches and halogen lights. Putting the DSL modem on a power line RFI filter (included in many surge suppressors -- see "Surge/lightning suppression for cable/DSL") may or may not solve the problem.

If you do determine that a lighting dimmer switch is causing interference, you may be able to solve the problem by replacing it with a switch that generates less interference (i.e., a switch with better RFI filtering). Cheap switches may have little or no RFI filtering; better switches that normally have good RFI filtering may be defective. Switches with good filtering are made by a number of manufacturers, including:

For more information on dimmer switch RFI, see the Lutron FAQ (frequently asked question), "What is radio frequency interference (RFI)?"

See "Other sources of DSL interference" for similar problems caused by switching power "bricks" (external AC power adapters).

For general technical information on tracking down sources of RFI, see "Track and Solve Electrical Interference" by the ARRL (American Radio Relay League, Inc.).

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Other sources of DSL interference 

AM radio stations
According to Nortel Networks, ADSL speeds can be cut by up to 40% by AM radio station interference, a problem that may affect up to 15% of ADSL subscribers. See "AM radio creates ADSL static".
Bridge taps
A "bridge tap" is an unconnected cable that is spliced into your telephone line, usually the remains of a connection to a different telephone subscriber. Bridge taps can cause a variety of problems. Locating and removing them can be difficult and expensive.
DAML
Digital Added Main Line (DAML) telephone line-multiplexors (used to provide more than one phone line over a single cable pair) directly interfere with ADSL and other types of modems. The symptoms with an Alcatel 1000 include ADSL drop/reconnect cycles when the analog line goes offhook, and when automated nightly C.O. line testing occurs. (See "ADSL Readiness")
Disturbers
A "disturber" is another high-speed data service (e.g., ISDN, T-1, DSL) in the same cable bundle as your DSL service. Although DSL is designed to tolerate a certain amount of disturbance, too much disturbance can cause problems, particularly when combined with other sources of interference. Common symptoms of interference from a disturber are DSL problems that occur only at certain times of the day.
MTU
The Maintenance Test Unit (MTU) is a device installed at your location, used to remotely test your phone line. Unfortunately, it can seriously interfere with data communications. Any MTU should be removed.
Power "bricks"
Old style power "bricks" (external AC power adapters) based on transformer technology are usually fine, but some poor new style power "bricks" based on switching technology generate RFI interference much like poor dimmer switches (see "DSL problems caused by your own lighting"). These new style power bricks tend to be noticeably smaller and lighter than the old style. Replacing such a switching-type power brick with a transformer-type power brick (available at electronics suppliers; e.g., Radio Shack) should solve the problem. Be sure to get the proper current capacity as well as the proper output voltage.

For more information, see "Exorcizing DSL Demons" (from Outside Plant).

Unfortunately, there is not much that a DSL subscriber can do about many of these sources of interference (except as noted) other than asking the DSL provider to try to correct any problems.

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Sync-nosurf (green light lockup) problem

The Alcatel 1000 ADSL modem has a nasty habit of locking up (not passing data) even though the sync light is green. Other ADSL modems that also appear to exhibit this problem include:

When this happens, normal Internet connectivity is lost. Often the only way to recover is to manually remove power from the modem; wait several seconds; and then restore power, whereupon the modem reinitializes, resyncs, and resumes normal operation.

Another possible aspect of this problem is ARP (Address Resolution Protocol). It has been reported (but not verified by this author) that the Alcatel ADSL modem will substitute its own MAC address for that of the "gateway" when the DSL link is down. Since ARP entries are cached, this could result in packets not reaching the gateway for some time after the DSL link has recovered (i.e., until the bogus entry for the gateway expires from the cache). If you have a Windows machine networked directly to an Alcatel modem (i.e., not through a router), you can check your ARP cache with the "ARP -a" command, and you can delete specific entries (e.g., your gateway) from the cache with the "ARP -d" command. (Restarting your computer or your router is a clumsy but sure way to flush the entire ARP cache.)

For more technical information on this problem, see "Alcatel ADSL Modem Sync/NoSurf" by Lawrence Baldwin of myNetWatchman.com.

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Windows reboot problems with Alcatel SpeedTouch USB

(Thanks to Bob Carter for passing this tip along.)

According to Alcatel:

Some PC's running Win98, Win98 SE or Win ME get a corrupted registry after 3 or 4 reboots or unplug-replug sequences. This causes windows to crash or a hangup while rebooting.

For a fix, see the Alcatel FAQ SpeedTouch USB, Q10 in the "Windows Drivers" section.

(This kind of problem is one of the reasons that Ethernet is preferred over USB -- see "Which is better: Ethernet or USB or PCI?".)

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Multiple security vulnerabilities in Alcatel modems

Researchers associated with the San Diego Supercomputer Center at the University of California, San Diego have identified multiple implementation flaws in the Alcatel Speed Touch ADSL "modem" (actually an ADSL-Ethernet router/bridge). These flaws can allow an intruder to take complete control of the device, including changing its configuration, uploading new firmware, and disrupting the communications between the telephone central office providing ADSL service and the device.

For more information, see:

Important things to know:

In the meantime you can:

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ADSL Modem Guide (DMT issue 2)

Most ADSL deployments are based on Alcatel-compatible hardware. On such systems, you generally should be able to use any device that is compliant with (ANSI T1.413) DMT issue 2.

Important notes:
1 May be compatible with Alcatel, but no specific mention of Alcatel compatibility.
2 Sold only through service providers, not directly to end users.
3 According to Cisco, the 677 is not compatible.
4 According to a report, the Remote 810 is not compatible.

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What is IFITL? FTTC? FTTH?

IFITL stands for "integrated fiber in the loop," another name for "fiber in the loop" (FITL) or "fiber to the curb" (FTTC). This use of optical fiber can extend the reach and/or increase the speed of DSL by shortening the length of the final copper wire run to the home. When fiber reaches all the way to the home, the term becomes "fiber to the home" (FTTH), which can provide very high-speed service without DSL (which works only over copper wire), typically using ATM. For more information, see:

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Other DSL Resources

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What is "Wireless DSL?"

If the most common forms of broadband Internet -- Cable, DSL, and Satellite -- are unavailable and/or unattractive in your area, are you out of luck? Maybe not. Fixed terrestrial (as opposed to satellite) wireless, sometimes called "Wireless DSL," is a group of newer technologies that are starting to be deployed in some areas. Here's a quick guide to this type of service:

  1. "Wireless DSL" is not really DSL
    Fixed terrestrial wireless is capable of providing a broadband experience comparable to DSL, which is why it's sometimes called "Wireless DSL." However, the term DSL (Digital Subscriber Line) properly refers only to data service over standard copper telephone lines. In addition, there are important technical differences between fixed terrestrial wireless and DSL. Hence the term "Wireless DSL" is descriptive but not really accurate.
  2. There's more than one flavor of fixed terrestrial wireless
    Some of the principal technologies:
    1. BroadLink is based on local transceivers with relatively short range (about 4 miles) using the same 11 Mbps IEEE 802.11b technology used in wireless local area networking. The service is somewhat similar to cellular data, and is sold only through ISPs (not direct from BroadLink). Service is currently available in Santa Rosa, California (Sonic.net), Stockton, California (InReach), and is undergoing market trials in Atlanta, Georgia.
    2. Sprint Broadband Direct (no longer available).
    3. WaveRider has both line-of-sight and non-line-of-sight products.

    Service in the first two cases is available only to those with direct line-of-sight to a transceiver, although the technology used by BroadLink tends to provide more complete coverage (less line-of-sight interference) and to be more scalable (fewer subscribers per transceiver). The balance of this section will focus on the technology used by BroadLink.

  3. Like Satellite Internet, you need an external antenna
    The BroadLink antenna is about 14.5 inches square. Although it must be mounted with direct line-of-sight to the local transceiver, alignment is less critical than for Satellite Internet. Currently the necessary electronics are mounted in a separate box located near the antenna [picture]; in the next generation the electronics will be smaller and mounted on the back of the antenna. Connection to the subscriber's computer is by standard Category 5 network cable, which carries data as well as power for the electronics.
  4. Like Cable Internet, the service is shared
    Unlike true DSL, where each subscriber has a dedicated connection, but like Cable Internet, Wireless DSL subscribers share the capacity of a given transceiver. Hence, it is possible for the service to slow down during periods of high usage if the capacity has been oversubscribed. Nevertheless, like Cable Internet, performance is usually very good. Like typical DSL, the service objective is 1.5 Mbps (down, 128 Kbps up).
  5. It's not really 11 Mbps
    Only one transmitter can be sending at any one time on a given segment (serviced by a given local transceiver). Since data cannot flow in both directions (up and down) at the same time, real throughput is much less the raw 11 Mbps transmission speed -- on the order of about 6 Mbps. Nevertheless, that's still enough capacity (augmented by "fairness" algorithms in the network) to provide good service to dozens of typical subscribers on a given segment.
  6. Latency is much better than satellite
    Although the other principal form of wireless broadband, Satellite Internet, suffers from very high latency (due to the long round trip that signals must travel) that can adversely affect certain types of Internet use (e.g., real-time gaming), Wireless DSL has latency ("ping" time) comparable to Cable Internet and DSL (typically on the order of 40 ms or less).
  7. Premium service
    BroadLink service is available with static IP, either bridged or routed. This means that, for example, you can easily run your own server.
  8. Good security
    The basic security of IEEE 802.11b networking (used by BroadLink) is based on WEP (Wired Equivalent Privacy). The bad news is that WEP has been shown to be not terribly secure. The good news is that BroadLink has implemented additional security that keeps subscribers from snooping the traffic of other subscribers.
  9. How to get the most out of Wireless DSL
    Because it's so similar to Cable Internet and to DSL, Wireless DSL can be easily optimized using the methods described in this document.
  10. Another wireless Internet option
    Metricom's Ricochet service, which has been deployed in a number of areas, provides a different tradeoff for wireless Internet access, the benefit of roaming mobile service (rather than fixed point) at the expense of speed (128 Kbps versus 1.5 Mbps). Unfortunately, Metricom has filed for Chapter 11 bankruptcy protection, and the future of the Ricochet service is uncertain.

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Surge/lightning suppression for cable/DSL

Power surges, particularly those caused by nearby lightning strikes, can damage your cable or DSL modem, or even your computer. A surge/lightning suppresser can provide protection, but unfortunately many of the devices sold in retail stores, particularly the less expensive ones, are not terribly effective. Another problem is that they typically aren't designed for the higher speeds of Cable Modems and DSL. If you care about such protection, you may want to consider a higher quality "industrial grade" unit specifically designed for high-speed data; good sources of such products include: Good sources of power line only commercial grade surge suppressors include:
Power line surge suppressor standards
At a minimum, make sure that any point of use surge suppressor is UL 1449 Second Edition listed/recognized at a suppressed voltage rating (SVR) of 330 volts. For endurance, the surge suppressor should also be Classified in Accordance with ANSI/IEEE C62.41-1991, Recommended Practices. UL 1449 listed products are not necessarily classified for endurance.
Telecommunications network suppressor standards
At a minimum, make sure that any point of use surge suppressor is UL 497 listed/recognized.

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Shopping On-line

All products are not the same -- cheaper products may not be such a bargain when you take into account functionality, quality, and support. Even on the same product, the best price may not be the best deal -- consider also:

  • Stock status
  • Shipping & handling
    • Costs (vary widely)
    • Methods (ground, air)
    • Speed (order to ship delay)
  • Sales tax (may or may not be charged)
  • Return policies
  • Customer service
  • Credit card policies
  • Privacy and/or spam

Recommended on-line merchants (for value and service):

Good deals:

Hard to find & unusual items:

Auctions:

You may find a great deal, or you may actually wind up paying more than retail. The seller might be reputable, or a fly-by-night con artist. Be careful! Auctions:

How do you know you will actually get what you won and paid for? You can lower your risk with an on-line payment/escrow service:

Not recommended on-line merchants:

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TCP/IP Resources

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Wireless Roaming

As wireless networking based on IEEE802.11b becomes ever more popular, retail businesses, groups, and even individuals are starting to provide wireless Internet access to the public, often at no cost (at least for now). All you need is a notebook computer or PDA with a "WiFi" transceiver card. For more information see:

See also:

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Other Resources

Caveat: The following information has not been verified by this author. USE AT YOUR OWN RISK.

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