Date: Tue, 29 Jan 2008 16:30:19 +1300 From: "Brent Jones" <brent.jones@otago.ac.nz> To: "Olivier Nicole" <on@cs.ait.ac.th>, <siraj.shaikh@gmail.com> Cc: freebsd-questions@freebsd.org Subject: RE: IP Aliasing Message-ID: <31AE442CCBC1094ABC40CE85B0149F0652375D@MAIL1.registry.otago.ac.nz> In-Reply-To: <200801290234.m0T2YtLn074403@banyan.cs.ait.ac.th> References: <3b2ddd940801280627m6d747cd1g27682bcd9e50ceb7@mail.gmail.com> <200801290234.m0T2YtLn074403@banyan.cs.ait.ac.th>
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> > 2) if an interface is configured with an alias address, then what > > address is shown on the traffic leaving this interface? So, for > > example, if I were to ping this machine on its primary address, I > > expect to get a response from the primary address of the interface. > > What happens if I ping an alias address, would I get a response from >=20 > By default exiting traffic is using the primary address (the one > defined with no keyword alias in the ifconfig). I think there is a way > to choose the exiting IP. >=20 > When a paket is responding, it use the same IP that was used in the > query (else any firewall would be confused in the way). Just a note on this question/answer: You can configure a FreeBSD machine to use random IP addresses from the available pool of configured IP addresses when machines traverse the NATted firewall. If you choose this option, you may run into problems with people behind your firewall/router having difficulty connecting to web sites that use session authentication, as the IP address of the source machine will be constantly changing with each click of links on the destination web site. (This caught me out for months before I realised what was happening.) Cheers, Brent
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