CS401 Page 1

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.

2
Web Server Installation Statistics

• http//www.netcraft.co.uk/survey/

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 --prefixPREFIX
• 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
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 8ltlast 3 digits
  of SSgtAdd Port 8ltlast 3 digits of SSgt to
  httpd.conf.

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

6
Apache Testbed LAN Setup

• /usr/www/lan_setup script for bilbo
• ifconfig eth0 128.198.192.182
• ifconfig eth00 128.198.192.172
• ifconfig eth01 128.198.192.202
• Or on linuxconf for bilbo, selectconfig
  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).

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 eth01 down to shut down the IP
  aliase.
• Use ifconfig eth01 up to bring it up again.

8
Apache Web Site Exercises

• Each site.ltexercisegt 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.ltnamegt
  -X-d for the site directory, -X single process
  execution
• Edit the httpd.conf file. Add the following
  lines Port 8ltlast 3 digits of your SSgt
  TransferLog /mpc/home/ltlogingt/sites/site.ltnamegt/lo
  gs/access_log
• In go shell script file, replace xxSITESxx with
  /mpc/home/ltlogingt/sitesreplace ltnamegt with the
  corresponding site name.
• Type go to start the web server

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 ltsitegt/logs/error_log or ps aux
  grep webuser to see if the server is configured
  and running.Sat Feb 7 202357 1998 Server
  configured -- resuming normal operations
  orwebuser 13013 0.0 2.2 1260 704 ? S
  2023 000 httpd -d /home/cs401
• tail -f ltsitegt/logs/access_log to see the
  processing results of client requestsusrp16.uccs.
  edu - - 07/Feb/1998032116 -0700 "GET /
  HTTP/1.0" 200 170
• Use a browser (on vinci or other machines) to
  accessthe server a few times with url
  http//bilbo8345/
• kill cat ltsitegt/logs/httpd.pid to terminate
  web server.note that it is back quote and not

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

11
Block Directives

• Directives that limit the application of other
  directives.
• Specify by a group like a tag section in html.
• ltVirtualHost hostportgt...lt/VirtualHostgt
• ltVirtualHostgtltDirectory dirgt, ltFiles filegt,
  ltLocation URLgt in ascending order of authority.
  ltLocationgt can overwrite others.
• dir, file, URL can specify using wildcards and
  full regular expressions preceded by

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
• ServerAdminemail 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 rotatelogsThe file is
  relative to the server root directory(specified
  in httpd -d ltserver rootgt or /usr/local/etc/httpd)

13
Directives

• KeepAlive onoff(on) keep connection alive for
  n requests before terminate provided they come in
  before timeout. n is defined in
  MaxKeepAliveRequests ltngt(100) directive
• KeepAliveTimeout ltngt(15) wait for the next
  request for n seconds before terminate the
  connections.
• Timeout ltngt(300) max. time in sec for a block
  data.
• HostNameLookups onoffdouble(off) do reverse
  DNS lookup for logging the domain name of the
  request.
• MaxClients ltngt(256) the limit of of
  simultaneous requests (hence the of child
  processes).
• MaxRequestsPerChild ltngt(0) Spare(child) server
  dies after ltngt requests, avoid mem leak. 0 mean
  infinite requests.
• Min/MaxSpareServers ltngt(5/10) of Idle child
  servers
• StartServers ltngt(5) sets the number of child
  server processes created on startup.

14
Homework3 Exercise 1Site.toddle and Site.simple

• cp -r /mpc/home/www/sites
  /mpc/home/ltlogingt
• Edit the httpd.conf in conf directoryDocumentRoot
  /usr/www/site.simple/htdocs ?DocumentRoot
  /mpc/home/ltlogingt/sites/site.simple/htdocs Port
  8ltlast 3 digits of your SSgtTransferLog
  logs/access_log
• Edit go shell script httpd -d
  /mpc/home/ltlogingt/sites/site.ltnamegt -Xgo 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.edultportnogt/ or
  http//frodo.uccs.edultportnogt/ depending which
  machine
• Check the access_log file. Keep them as record

15
Homework3 Exercise 1

• User webuser
• Group webgroup
• ServerName bilbo.uccs.edu or frodo.uccs.edu
• DocumentRoot /mpc/home/ltlogingt/sites/site.toddle/h
  tdocs
• Port 8ltlast 3 digits of your SSgt
• TransferLog logs/access_log

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.eduadd Port
  8ltlast 3 digits of SSgt
• 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.confreplace
  sales.butterthlies.com with b2b.uccs.eduReplace
  Listen sales.butterthlies.com80 withListen
  b2b.uccs.edu8ltlast 3 digits of SSgt
• httpd -d /mpc/home/ltlogingt/sites/site.twocopy/cust
  omers -X
• httpd -d /mpc/home/ltlogingt/sites/site.twocopy/sale
  s -X

17
Web Hosting

• Named-based vs. IP-based Virtual Host
  (VH)HOST ltnamegt a unique IP address for
  each VHon metaheader different to
  support a lot of VHsold browsers notsupport
  this
• Use ltVirtualHost hostnameportgt 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.

18
Site.Virtual/Name-based

• cd /mpc/home/ltlogingt/sites/site.virtual/Name-base
  d
• edit the httpd.conf in conf directory
• NameVirtualHost 192.168.123.2 ?NameVirtualHost
  128.198.192.182Port 8ltlast 3 digits of SSgt
• ltVirtualHost www.butterthlies.comgt ?ltVirtualHost
  bilbo.uccs.eduportnogtHere portno is 8ltlast 3
  digits of your SSgt
• ServerAdmin sales_at_butterthlies.com ? ServerAdmin
  ltlogingt_at_cs.uccs.edu
• /usr/www ? /mpc/home/ltlogingt/sites/
• ltVirtualHost sales.butterthlies.comgt
  ?ltVirtualHost sales-bilbo.uccs.eduportnogt
• Go to start virtual hositng.

19
Site.Virtual/IP-based

• cd /mpc/home/ltlogingt/sites/site.virtual/IP-based
• edit the httpd.conf in conf directory
• Add Port 8ltlast 3 digits of SSgt right after
  Group webgroup
• ltVirtualHost 192.168.123.2gt ?ltVirtualHost
  128.198.192.182portnogtHere portno is 8ltlast 3
  digits of your SSgt
• ServerName bilbo.uccs.edu
• ServerAdmin sales_at_butterthlies.com ? ServerAdmin
  ltlogingt_at_cs.uccs.edu
• /usr/www ? /mpc/home/ltlogingt/sites/
• ltVirtualHost 192.168.123.3gt ?ltVirtualHost
  128.198.192.172portnogt
• ServerName b2b.uccs.edu

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 128.198.192.1828888
• Port 8888
• ltVirtualHost bilbo.csnet.uccs.edu8888gt
• DocumentRoot /mpc/home/guest/sites/site.virtual/ht
  docs/customers
• ltVirtualHost salesbilbo.csnet.uccs.edu8888gt
• DocumentRoot /mpc/home/guest/sites/site.virtual/ht
  docs/salesmen
• ltVirtualHost 128.198.192.1728888gt
• DocumentRoot /mpc/home/guest/sites/site.virtual/ht
  docs/salesmen

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
• ltVirtualHost 128.198.192.1827888gt
• DocumentRoot /mpc/home/guest/sites/site.virtual/ht
  docs/customers
• ltVirtualHost 128.198.192.1828888gt
• DocumentRoot /mpc/home/guest/sites/site.virtual/ht
  docs/salesmen

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.

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.

24
Homework 3 Problem 3

• Explain why it is possible not to require a new
  IP address to host a customers web site, even
  though it has a unique domain name.