Workshop

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I discuss netstat -r (which shows you which route the UNIX host thinks packets should take
through the network) as well as traceroute in Hour 14, “Router and Switch Basics.” The
traceroute command is a great way to find the routers that a packet needs to go through in order to
get from point A to point B. The thing to know about it under UNIX is that not all implementations of
UNIX have it. Most do, but there are still one or two proprietary implementations of UNIX that do not.
However, you can always get it from ftp://ftp.ee.lbl.gov/traceroute.tar.Z. You’ll need to be reasonably
comfortable with the UNIX command line to use this, because it comes in source code form—it requires
you to use the tar command to extract the source code and the make command to compile it.
Summary
UNIX hosts are typically reliable servers used to house databases, client/server applications, and Telnet
sessions. They’re also awesome for running Web and FTP servers.
Most UNIX services run through background programs called daemons. Some service problems can be
solved by stopping and starting a daemon process.
Many times, you’ll need to run commands as the root user. To get comfortable and become good at this,
you’ll probably want to set up a play system, where you’re able to learn from your mistakes without
affecting a crucial system.
You can keep track of the services and clients running on your system through the netstat -a
command. A busy UNIX system can have hundreds or thousands of sockets open at any given time; you
can track down the socket you’re looking for by using netstat in conjunction with the grep
command.
Ping is your best friend (as usual with TCP/IP troubleshooting) in determining whether a problem lies
with the UNIX server, the network, or the router.
Workshop
Q&A
Q I can’t get to a file on my G: drive (it’s mapped to my UNIX server’s /home file system), but the
person next to me can. When I log in as her, I can get to the file. What’s up with this?