[users@httpd] Apache 1.3.27 ProxyPass/VirtHost problem

[Mathias Koerber <ma...@koerber.org>]

I have a problem with my Apache 1.3.27 (Linux) to forward requests from
the outside network to a host on the inside network. Both servers
serve the same virtual hosts (albeit using diff IP addresses).

General setup:

Firewall/Main Webserver:
	Apache 1.3.27

	# This server is also used as proxy for my intranet to proxy requests #
	to the outside:

	ProxyRequests On
	proxyRemote * http://proxy.myisp.example:8080

	ExpiresActive   on
	ExpiresDefault "modification plus 1 day" ExpiresByType image/jpeg "access
	plus 1 day" ExpiresByType text/html "modificatin plus 14 days"

	# To enable the cache as well, edit and uncomment the following lines:

	#CacheRoot /usr/local/apache/var/proxy CacheRoot /u6/proxy
	CacheSize 5
	CacheGcInterval 4
	CacheMaxExpire 24
	CacheLastModifiedFactor 0.1
	CacheDefaultExpire 1

	# only allow the intranet site to use the proxy <Directory proxy:*>
	order deny,allow
	deny from all
	allow from 172.22.22.0/24 localhost 127.0.0.1 </Directory>

	# This server then is set up to serve multiple virtual hosts to
 	# the outside world. A few are still hosted on this machine
	# while others are to be transparently forwarded to the # internal
	webserver which will server those also in a virtual # host setup


	# The WWW server
	NameVirtualHost 172.22.22.1:80
	NameVirtualHost mypublicIP:80
	NameVirtualHost 127.0.0.1:80

	# new HOME
	<Virtualhost 172.22.22.1 mypublicIP:80 127.0.0.1:80> ServerAdmin
	webmaster@site.example
	ServerName home.site.example
	ErrorLog logs/home-error_log
	TransferLog logs/home-access_log
	CustomLog logs/home-custom_log request

	# allow the outside world to access this (need to override the global #
	proxy perms denying the outside world for this! <Directory
	proxy:http://home.site.example*> order deny,allow
	allow from all
	</Directory>

	# now pass all requests for home.koerber.org to the internal #
	home.koerber.org. Hopefully it resolves to the internal IP # address here
	(it does, at least from the commandline/dig :-) ProxyPass /
	http://home.site.example/ </VirtualHost>

	# and the WIKI
	<Virtualhost 172.22.22.1 mypublicIP:80 127.0.0.1:80> ServerAdmin
	webmaster@site.example
	ServerName testwiki.site.example
	ErrorLog logs/testwiki-error_log
	TransferLog logs/testwiki-access_log
	CustomLog logs/testwiki-custom_log request

	<Directory proxy:http://testwiki.site.example*> order deny,allow
	allow from all
	</Directory>

	ProxyPass /     http://testwiki.site.example/ </VirtualHost>

The actual webserver is set up similar, ie it has virtual host
definitions. This too is Apache 1.3.27:

	NameVirtualHost *

	# the first VH is the default
	<VirtualHost *>
	ServerName home.site.example
	ServerALias ...
	DocumentRoot ...
	</VirtualHost>

	# the next VH is a TWIKI and needs its own script-dirs etc: <VirtualHost
	*>
	ServerName testwiki.site.example
	DocumentRoot /var/www/testwiki/html

	<Directory "/var/www/testwiki/html">
	    Options Indexes FollowSymLinks
	    AllowOverride None
	    Order allow,deny
	    Allow from all
	</Directory>

	<IfModule mod_alias.c>
	    Alias /icons/ "/var/www/testwiki/icons/"

	    <Directory "/var/www/testwiki/icons">
	        Options Indexes MultiViews
	        AllowOverride None
	        Order allow,deny
	        Allow from all
	    </Directory>
	    ScriptAlias /cgi-bin/ "/var/www/testwiki/cgi-bin/"

	    <Directory "/var/www/testwiki/cgi-bin">
	        AllowOverride None
	        Options None
	        Order allow,deny
	        Allow from all
	    </Directory>

	</IfModule>

	ScriptAlias /twiki/bin/ "/u1/twiki/testwiki/bin/" Alias /twiki/
	"/u1/twiki/testwiki/"
	<Directory "/u1/twiki/testwiki/bin">
	   Options +ExecCGI
	   SetHandler cgi-script
	   Allow from all
	   AllowOverride All
	</Directory>
	<Directory "/u1/testwiki/pub">
	   Options FollowSymLinks +Includes
	   AllowOverride None
	   Allow from all
	</Directory>
	<Directory "/u1/twiki/testwiki/data">
	   deny from all
	</Directory>
	<Directory "/u1/twiki/testwiki/templates">
	   deny from all
	</Directory>
	</VirtualHost>

When I directly connect to the internal server (home.site.example resolves
directly to it on the intranet), everything works fine.

Whenever I connect to the public IP address from an outside system and
issue a HTTP/1.2 GET, like this:

	$ telnet mypublicIP 80
	Trying mypublicIP...
	Connected to mypublicIP.
	Escape character is '^]'.
	GET http://home.site.example/twiki/Main/ HTTP/1.1 Host: home.site.example


the external webserver goes into a loop trying to look up the page in its
cache instead of forwarding it to the internal server:

home-error_log:
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1045): Request for 
http://home.site.example/twiki/Main/, pragma_req=(unset), ims=0
	[Wed Jan 8 21:53:22 2003] [debug] proxy_util.c(1450): File 
/u6/proxy/u/A/Y/cLSoEwNm2OH6z7H71UA not found
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1308): Local copy not 
present or expired. Declining.
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1045):	Request for 
http://home.site.example/twiki/Main/, pragma_req=(unset), ims=0
	[Wed Jan  8 21:53:22 2003] [debug] proxy_util.c(1450): File 
/u6/proxy/u/A/Y/cLSoEwNm2OH6z7H71UA not found
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1308): Local copy not 
present or expired. Declining.
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1045):	Request for 
http://home.site.example/twiki/Main/, pragma_req=(unset), ims=0
	[Wed Jan  8 21:53:22 2003] [debug] proxy_util.c(1450): File 
/u6/proxy/u/A/Y/cLSoEwNm2OH6z7H71UA not found
	[Wed Jan  8 21:53:22 2003] [debug] proxy_cache.c(1308): Local copy not 
present or expired. Declining.

ad infinitum (until the server quickly reaches some limit and dies)

How can I make it NOT try to always look up this URL in its cache (or go
and fetch the data as it is not found in the cache)?

I tried adding
	NoCache home.site.example
to the global proxy configuration and to the VirtualHost definition for
home.site.example, w/o luck. I also tried using ProxyRequests On

I am stumped. Can anyone help point out the problem?

is there a way to debug Apache's internal rewriting/proxying and DNS
lookups etc?

thanks


-- 
Mathias Koerber
mathias@koerber.org

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