1. Apache Web Server
• A PAtCHy server: developed by the Apache group
formed 2/95 around a number of people who provided
patch files for NCSA httpd 1.3 by Rob McCool.
• History-http://www.apache.org/ABOUT_APACHE.html
• First official public release (0.6.2) in April 1995
• Add adaptive pre-fork child processes (very important!).
• Modular structure and API for extensibility (Bob Thau)
• Port to multiple platforms. Add documentation.
• Apache 1.0 was released on 12/1/95.
Pass NCSA httpd to be #1 server in Internet.
4/2/2010 C. Edward Chow CS401 Page 1

2. Web Server Installation Statistics
• http://www.netcraft.co.uk/survey/
4/2/2010 C. Edward Chow CS401 Page 2

3. Compiling Apache_1.3.12
• Download apache_1.3.12.tar.gz from
http://www.apache.org/dist or closer mirror sites
• $tar xzvf apache_1.3.12.tar.gz
• $ ./configure --prefix=PREFIX
• $ make
• $ make install
• $ PREFIX/bin/apachectl start
• Here PREFIX is the prefix of the directory containing
the distribution, typically it is /usr/local/apache.
4/2/2010 C. Edward Chow CS401 Page 3

4. CS401 Apache Testbed
• bilbo.uccs.edu and frodo.uccs.edu are installed with
Apache1.3.12.
• /mpc/home/www/sites contains the configuration files
of various web sites contained in the CD-ROM of
Apache text.
• See http://cs.uccs.edu/~cs401/cs401lab.html for
more detail on how to carry out the exercise.
• Copy /mpc/home/www/sites to your directory.
• To avoid conflict, use port # = 8<last 3 digits of SS#>
Add “Port 8<last 3 digits of SS#>“ to httpd.conf.
4/2/2010 C. Edward Chow CS401 Page 4

5. Apache Exercise Setup
• Replace domain name/IP address on 3rd left Linux PC
www.butterhlies.com 192.168.123.2 with bilbo.uccs.edu 128.198.192.182
sales.butterthlies.com 192.168.123.3 with b2b.uccs.edu 128.198.192.172
www.faraway.com 192.168.124.1 with wait.uccs.edu 128.198.192.202
• Replace domain name/IP address on 4th left Linux PC
www.butterhlies.com 192.168.123.2 with frodo.uccs.edu 128.198.192.183
sales.butterthlies.com 192.168.123.3 with feline.uccs.edu 128.198.192.173
www.faraway.com 192.168.124.1 with walden.uccs.edu 128.198.192.203
• Replace domain name/IP address on 5th left Linux PC
www.butterhlies.com 192.168.123.2 with gandalf.uccs.edu 128.198.192.194
sales.butterthlies.com 192.168.123.3 with gallop.uccs.edu 128.198.192.174
www.faraway.com 192.168.124.1 with wind.uccs.edu 128.198.192.204
4/2/2010 C. Edward Chow CS401 Page 5

6. Apache Testbed: LAN Setup
• /usr/www/lan_setup script for bilbo:
ifconfig eth0 128.198.192.182
ifconfig eth0:0 128.198.192.172
ifconfig eth0:1 128.198.192.202
• Or on linuxconf for bilbo, select
config | networking | IP aliases for virtual hosts | eth0. Type in
128.198.192.172, 128.198.192.202 for IP aliases
(I have not succeeded in using the above method.)
• Normally we skip lan_setup. We will share the same lan_setup.
Run the above lan_setup if you find the computer is configured
incorrectly (through ifconfig).
4/2/2010 C. Edward Chow CS401 Page 6

7. Ifconfig command
• Interface configuration command.
• There is an equivalent command ipconfig on win32.
• In Redhat linux, it is in /sbin. I have modified
/etc/profile to include that directory in $PATH.
• Use ifconfig to show the status
• Use ifconfig eth0:1 down to shut down the IP aliase.
• Use ifconfig eth0:1 up to bring it up again.
4/2/2010 C. Edward Chow CS401 Page 7

8. Apache Web Site Exercises
• Each site.<exercise> directory contains
– conf: configuration files, httpd.conf, srm.conf, access.conf,
mime.types
– htdocs: contains web pages, scripts
– logs: access_log, error_log, httpd.pid, (referer_log, agent_log)
– go: alias of “httpd -d xxSITESxx/site.<name> -X”
-d for the site directory, -X single process execution
• Edit the httpd.conf file. Add the following lines
Port 8<last 3 digits of your SS#>
TransferLog /mpc/home/<login>/sites/site.<name>/logs/access_log
• In go shell script file, replace xxSITESxx with /mpc/home/<login>/sites
replace <name> with the corresponding site name.
• Type go to start the web server
4/2/2010 C. Edward Chow CS401 Page 8

9. Examine httpd Configuration
• To enhance the security, webuser is created to run httpd
Add “User webuser” and “Group webgroup” to httpd.conf.
• “tail -f <site>/logs/error_log” or “ps aux | grep webuser” to
see if the server is configured and running.
[Sat Feb 7 20:23:57 1998] Server configured -- resuming normal operations or
webuser 13013 0.0 2.2 1260 704 ? S 20:23 0:00 httpd -d /home/cs401
• “tail -f <site>/logs/access_log” to see the processing
results of client requests
usrp16.uccs.edu - - [07/Feb/1998:03:21:16 -0700] "GET / HTTP/1.0" 200 170
• Use a browser (on vinci or other machines) to access
the server a few times with url = http://bilbo:8345/
• “kill `cat <site>/logs/httpd.pid`” to terminate web server.
note that it is back quote ` and not „
4/2/2010 C. Edward Chow CS401 Page 9

10. Httpd Configuration File
• Apache uses a set of (73) directives to describe to
httpd how the web site should be configured.
http://www.apache.org/docs/mod/directives.html
Each Apache configuration directive is described using a common
format that looks like this:
Syntax: directive-name some args
Default: directive-name default-value
Context: context-list
Override: override
Status: status
Module: module-name
Compatibility: compatibility notes
4/2/2010 C. Edward Chow CS401 Page 10

11. Block Directives
• Directives that limit the application of other directives.
• Specify by a group like a tag section in html.
• <VirtualHost host[:port]>
...
</VirtualHost>
• <VirtualHost…><Directory dir>, <Files file>,
<Location URL> in ascending order of authority.
<Location> can overwrite others.
• dir, file, URL can specify using wildcards and full
regular expressions preceded by “~”
4/2/2010 C. Edward Chow CS401 Page 11

12. List of Directives
• User, Group: specify user and group that httpd runs on.
• ServerName: hostname of server (for redirection URL)
• ResourceConfig, AccessConfig: for reading additional
related directives. Can be disabled by /dev/null as value
• Port: specify the port httpd run on
• ServerAdmin:email addr. for browser to do automatic replies.
• DocumentRoot:
• TransferLog, ErrorLog, PidFile: where access,error logs,
httpd.pid should be located. Can be file or pipe “|rotatelogs”
The file is relative to the server root directory
(specified in httpd -d <server root> or /usr/local/etc/httpd)
4/2/2010 C. Edward Chow CS401 Page 12

13. Directives
• KeepAlive [on|off](on): keep connection alive for n requests before
terminate provided they come in before timeout. n is defined in
MaxKeepAliveRequests <n>(100) directive
• KeepAliveTimeout <n>(15): wait for the next request for n seconds
before terminate the connections.
• Timeout <n>(300): max. time in sec for a block data.
• HostNameLookups [on|off|double](off): do reverse DNS lookup for
logging the domain name of the request.
• MaxClients <n>(256): the limit of # of simultaneous requests
(hence the # of child processes).
• MaxRequestsPerChild <n>(0): Spare(child) server dies after <n>
requests, avoid mem leak. 0 mean infinite requests.
• Min/MaxSpareServers <n>(5/10): # of Idle child servers
• StartServers <n>(5): sets the number of child server processes
created on startup.
4/2/2010 C. Edward Chow CS401 Page 13

14. Homework#3 Exercise 1:
Site.toddle and Site.simple
• “cp -r /mpc/home/www/sites /mpc/home/<login>“
• Edit the httpd.conf in conf directory
DocumentRoot /usr/www/site.simple/htdocs 
DocumentRoot /mpc/home/<login>/sites/site.simple/htdocs
Port 8<last 3 digits of your SS#>
TransferLog logs/access_log
• Edit go shell script
“httpd -d /mpc/home/<login>/sites/site.<name> [-X]“
go in the site.simple does not have –X.
• go will start the web server. Control-c will terminate it.
• Use browser to visit the site a few times. Remember to specify
the port # in url. For IE browser, type
http://bilbo.uccs.edu:<portno>/ or
http://frodo.uccs.edu:<portno>/ depending which machine
• Check the access_log file. Keep them as record
4/2/2010 C. Edward Chow CS401 Page 14

15. Homework#3 Exercise 1
User webuser
Group webgroup
ServerName bilbo.uccs.edu or frodo.uccs.edu
DocumentRoot /mpc/home/<login>/sites/site.toddle/htdocs
Port 8<last 3 digits of your SS#>
TransferLog logs/access_log
4/2/2010 C. Edward Chow CS401 Page 15

16. Site.twocopy
• Create two web servers: one serves customers; one for sales.
There are two directories in site.twocopy.
• In customers/conf/httpd.conf,
replace www.butterthlies.com with bilbo.uccs.edu
add Port 8<last 3 digits of SS#>
• Here BindAddress is used to specify the reception of request
from specific IP address (domain name) by this web server.
BindAddress bilbo.uccs.edu
• In sales/conf/httpd.conf
replace sales.butterthlies.com with b2b.uccs.edu
Replace Listen sales.butterthlies.com:80 with
Listen b2b.uccs.edu:8<last 3 digits of SS#>
• httpd -d /mpc/home/<login>/sites/site.twocopy/customers -X
• httpd -d /mpc/home/<login>/sites/site.twocopy/sales -X
4/2/2010 C. Edward Chow CS401 Page 16

17. Web Hosting
• Named-based vs. IP-based Virtual Host (VH)
HOST: <name> a unique IP address for each VH
on metaheader different to support a lot of VHs
old browsers not
support this
• Use <VirtualHost hostname[:port]> block directives
• Specify ServerAdmin, DocumentRoot, ServerName,
ErrorLog, TransferLog for individual VH
• Be aware that UNIX File Limits on # of file
descriptors. (default 64)  only support 32 VHs?
• You may want to increase # of child servers.
4/2/2010 C. Edward Chow CS401 Page 17

18. Site.Virtual/Name-based
• cd /mpc/home/<login>/sites/site.virtual/Name-based
• edit the httpd.conf in conf directory:
• NameVirtualHost 192.168.123.2 
NameVirtualHost 128.198.192.182
Port 8<last 3 digits of SS#>
• <VirtualHost www.butterthlies.com> 
<VirtualHost bilbo.uccs.edu:portno>
Here portno is 8<last 3 digits of your SS#>
• ServerAdmin sales@butterthlies.com 
ServerAdmin <login>@cs.uccs.edu
• /usr/www  /mpc/home/<login>/sites/
• <VirtualHost sales.butterthlies.com> 
<VirtualHost sales-bilbo.uccs.edu:portno>
• Go to start virtual hositng.
4/2/2010 C. Edward Chow CS401 Page 18

19. Site.Virtual/IP-based
• cd /mpc/home/<login>/sites/site.virtual/IP-based
• edit the httpd.conf in conf directory:
• Add Port 8<last 3 digits of SS#>
right after Group webgroup
• <VirtualHost 192.168.123.2> 
<VirtualHost 128.198.192.182:portno>
Here portno is 8<last 3 digits of your SS#>
• ServerName bilbo.uccs.edu
• ServerAdmin sales@butterthlies.com 
ServerAdmin <login>@cs.uccs.edu
• /usr/www  /mpc/home/<login>/sites/
• <VirtualHost 192.168.123.3> 
<VirtualHost 128.198.192.172:portno>
• ServerName b2b.uccs.edu
4/2/2010 C. Edward Chow CS401 Page 19

20. Site.Virtual/Mixed-based
• We can mix Name-based with IP-based virtual hosting.
• Change “IP-based” to “Mixed-based”. An error in config file.
NameVirtualHost 128.198.192.182:8888
Port 8888
<VirtualHost bilbo.csnet.uccs.edu:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/customers
<VirtualHost salesbilbo.csnet.uccs.edu:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
<VirtualHost 128.198.192.172:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
4/2/2010 C. Edward Chow CS401 Page 20

21. Port-based Virtual Hosting
• Can use one IP address to test many sites.
• Change IP-based to Port-based. An error in config file.
• Different ports map to different sites.
User webuser
Group webgroup
Listen 7888
Listen 8888
<VirtualHost 128.198.192.182:7888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/customers
<VirtualHost 128.198.192.182:8888>
DocumentRoot /mpc/home/guest/sites/site.virtual/htdocs/salesmen
4/2/2010 C. Edward Chow CS401 Page 21

22. Bonus Exercise #1
• After copying the site.virtual to the nfs mount dir and
executing the httpd, the access_log and error_log
files are empty.
• When use the directory mounted on local disk, there
are no problem.
• See the bonus exercise on
http://owl/~cs401/bonus.html
• Try to explain why this happens.
• A good answer gets 1 point count towards final
grade.
4/2/2010 C. Edward Chow CS401 Page 22

23. Homework #3 Exercise 2
• Run site.virtual/Name-based, site.virtual/IP-based,
and site.twocopy according to the textbook and verify
the results.
• Keep the access_log and error_log as records.
• Send me email when you finish both exercises.
4/2/2010 C. Edward Chow CS401 Page 23

24. Homework #3: Problem 3
• Explain why it is possible not to require a new IP
address to host a customer‟s web site, even though it
has a unique domain name.
4/2/2010 C. Edward Chow CS401 Page 24