System Administration for the Web:
Week 4 Lab
Some of you have complained that it's difficult to read Adobe Acrobat
documents on the Sun Rays. If you feel that the lag is unbearable,
you can print the lab using the printers located down the hall; your
inst account has a print quota of 100 pages. If you want to save trees,
we've also posted an HTML version of this lab on the class website.
You should be quite familiar with and capable of using Unix-based
systems at this point. In this lab, as well as the last, I did not
provide the syntax for any commands. From now on, it is your responsibility
to read the man pages or use a search engine to determine the syntax
for any of the commands presented in this lab.
Email your responses, the output of a command, or the commands you
used to perform a certain exercise (as appropriate) to dima@ocf.berkeley.edu
along with your inst account login, your OCF login, and your preferred
contact email address.
FTP
As explained in lecture, File-Transfer Protocol (FTP) is one of the
most common ways of distributing files over the Internet. Many FTP
servers allow anonymous access - that is, access to the general public.
In this section, you're going to connect to an FTP server and retrieve
a file.
As mentioned last week, the world's most popular DNS server is BIND,
the Berkeley Internet Name Domain. As you can probably figure out
from its name, BIND was developed at UC Berkeley. We're going to download
version 9.3.1 of BIND.
- [1]
- Use the ftp command to connect to ftp.isc.org,
the FTP server that hosts the BIND program. For anonymous access,
you must often provide "anonymous" as the login
and a random email address as the password.
- [2]
- Once you have successfully connected to the FTP server,
you will be able to get help by inputting - you guessed it - help.
Use help to determine what kind of commands you can use.
- [3]
- List the files in the current directory on the FTP server.
- [4]
- There shouldn't be anything interesting in the default directory.
The BIND program files can be found in the isc/bind9/9.3.1/
directory. Navigate to that path.
- [5]
- Once you're there, download the bind-9.3.1.tar.gz
file.
- [6]
- Suppose you wanted to get bind-9.3.1.tar.gz and
bind-9.3.1.tar.gz.asc from the FTP server. You could use
the command you used in the previous exercise twice, but there is
an easier way. Figure out how to get multiple files at once.
FTP works in both directions. You can download files from a server,
and you can upload files to a server.
- [7]
- Change to another directory. Try to upload a file into that
directory. What happens?
In most FTP server configurations, anonymous users are not allowed
to upload files. If they were allowed to upload files, anybody could
post any obscene or illegal file they wanted and get the server administrator
into trouble or consume all the server's disk space. In the final
project of this course, you'll be setting up an FTP server which will
allow authenticated users to download and upload files, so it's important
that you understand how FTP works.
- [8]
- Disconnect from ftp.isc.org.
In Section ![[*]](crossref.png)
you downloaded a copy of BIND. The file
you downloaded had the extension tar.gz, which means that it
is a gzipped tar archive. In the UNIX world, gzip is the equivalent
of zip compression, and tar is a method of packing files together.
- [1]
- Use gzip to decompress the BIND file.
You should now have a file named bind-9.3.1.tar. A tar archive
is a way of packing multiple files and directories together into a
single file. Unfortunately, tar does not support compression,
so people often compress tar archives with gzip or bzip2.
- [2]
- Extract bind-9.3.1.tar using tar.
- [3]
- Navigate to the bind-9.3.1 directory that was formed
when you extracted the tar archive.
- [4]
- There should be a make directory inside the bind-9.3.1
directory. Create a tar archive named make.tar of the make
directory and move the archive to your home directory.
- [5]
- Delete the bind-9.3.1 directory and any other files
related to BIND except for the archive that you just created. The
most efficient way to do this is to use the rm command with
the recursive and force parameters and a wildcard.
Ask your instructor for assistance if any of these terms confuse you.
Last week we had you use SSH to log into your OCF account from Soda
Hall. SSH was described as a nifty tool that allows you to log into
remote servers over an encrypted connection, among other things. We'll
be introducing those "other things" in this section.
SSH is a package of three tools: ssh, scp, and sftp.
You used the first tool last week to log into your OCF account. scp
is short for Secure CoPy, and sftp stands for Secure FTP.
- [1]
- scp can be used to copy files between computers.
Use scp to copy make.tar to your OCF account. Delete
make.tar from your inst account.
- [2]
- sftp operates very much like regular FTP. Use sftp
to connect to your OCF account and download make.tar.
The aforementioned operations are the most common uses for SSH, and
most system administrators use SSH on a daily basis. When you're working
on the final project, you'll find the need to transfer files to and
perform actions on your server, and SSH will make it possible. Consequently,
it is important that you become familiar and comfortable with SSH.
SSH has many other features such as tunneling. If you're interested,
you can search the web for information on how to use these features.
UNIX filesystems have many features that are not present in Windows
file-systems. For the purposes of this class, the only feature that
you need to know is the link. In a UNIX filesystem, files and
directories do not have to be unique - they can be placeholders that
point to other files or directories. There are two types of links:
hard and soft. We'll only focus on soft-links. If you
want to know the difference between the two types of links, please
consult your friendly search engine.
- [1]
- Locate the command to create links between files. Hint:
Using apropos is a good way to start.
- [2]
- Create a new text file and create a link to that file.
- [3]
- Edit the file by running a text editor on its link. Open
the actual file in a text editor. Compare what you see.
- [4]
- Create a new directory and create a link to that directory.
Move the text file you just created into that directory.
- [5]
- Print the contents of the directory using the link to that
directory. What do you see?
System Administration for the Web:
Week 4 Lab
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