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Infrequently Asked Questions

By Jeffrey Howard
All rights reserved unless noted otherwise

For a time, I was keeping notes to myself that were useful in administrating the small home network I was running. I put them online here in case they might help anyone else. I've since moved everything over to Pair Networks, so I haven't had anything new to add in some time. I'm leaving these pages up, because judging by the traffic, people are still finding them useful. I'm not maintaining them or adding to them, though.

Desktop Systems

• Compaq BIOS access is not intuitively obvious.
• Slow system clocks gradually fall behind real time.
• System clock displays incorrect time after every reboot.

Firewalls

• Choosing a firewall is easier than it seems.
• Packet Filter vs. Proxy, there is a difference.
• Port 33434 shows up in firewall logs often.
• CPAN downloads wait a long time and then time out.

Latex

• Latex margins do not print correctly.

Linux

• Ethernet card fails after using Microsoft Windows 98.
• Forgotten root passwords can be replaced.
• Giving other users root access is usually a bad idea. But if you must, here is an explanation how.
• KPPP asks for the root password. This can be inconvenient.
• Memory. How much of it is Linux seeing, anyway?
• A program cannot connect to display :0.0 if you use su to become root before running the program.
• Repeated events can be scheduled for regular intervals in the kernel.
• Routed refuses to exchange routing messages with peers over a PPP link.
• Shutdown is available to any user, though you'd prefer to limit it.
• TCPDump fails with an error message immediately on startup. The error message claims that a socket type is not supported.
• Telnet fails with an error message:

        Trying 127.0.0.1...
        Unable to connect to remote host: Connection refused
        

Name Resolution

• Connections to a machine pause or stall for a while at first. Afterwards, though, everything moves at full speed.
• "Lame server on ..." shows up in your system logs. What's a lame server?
• Nameservice for internal networks doesn't have any convention like the 192.168.0.0 address space for internal use only.
• SSH's X-Windows tunneling fails if /etc/hosts has a spurious entry.

Sendmail

• EXPN and VRFY should be disabled on your sendmail server.

TCP/IP Networking

• Network Classes A, B, C, and CIDR aren't complicated, but they lead to lots of confusion.
• Whois can tell you who owns an IP address block or a domain name.

Unix System Programming

• Posix signals have a lot of associated terminology. Here's a simple introduction.

Web Benchmarking

• WebStone 2.5 didn't compile on my vanilla RedHat 6.0 system.

X-Windows

• Changing display resolution under X-Windows can help, if your X display renders text that you need a microscope to read.

In addition to the random trivia above, I've found it helpful to keep track of a handful of web addresses. When I look into buying a product, I tend to collect a number of URLs about similar products for comparison. When I need to find the answer to a question online, I tend to jot down where I found the answer. Rather than organize these in bookmark folders in my browser, I'll start dropping them on a link page connected to the IAQ.