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From Christian Felsing <>
Subject Re: [users@httpd] Problem: Reverse Proxy Should Use a Specific IP(v6) Address on an Multihomed Interface
Date Thu, 07 Aug 2008 06:23:52 GMT
This is not a routing issue. Ethernet interface has multiple IP 
addresses from same subnet, so it does not matter which source address 
is selected by application for routing. Some applications provides a 
config option to use a specific IP address if it opens an IP connection 
with SYN and further operations on that socket. Intention is that dest. 
host should see a specific IP address, so it can decide if request is 
done via that reverse proxy or from other application on that host.

httpd "Listen" directive tells httpd to listen on a specific IP address 
only. It does not tell httpd to use a specific IP address for outbound 
connections which are created in reverse proxy operation.

Further investigation showed that httpd uses on Linux last configured 
IP(v6) address on interface. If there are different networks it uses 
last configured address in matching network. This is from point of 
routing ok, but may interfere other intentions regarding e.g. reverse 
DNS. For better understanding a small ascii graphic:

client --> rproxy --> dest. host

if dest. host resolves IP by reverse DNS it should get the right name 
which depends on outbound IP address used by rproxy.


Krist van Besien schrieb:
> This is most likely an operating system issue. You have to tell your
> server to route packets for your IPv6 hosts over the 1) interface.

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