|Randy Lewis (Kenneth R. Lewis)||Jan 24, 2002 1:03 pm|
|Bill Williamson||Jan 24, 2002 1:20 pm|
|Sysop||Jan 24, 2002 1:32 pm|
|Tim Hosking||Jan 24, 2002 1:53 pm|
|Sysop||Jan 24, 2002 1:59 pm|
|Randy Lewis (Kenneth R. Lewis)||Jan 24, 2002 2:11 pm|
|Johannes Erdfelt||Jan 24, 2002 2:17 pm|
|Aly S.P Dharshi||Jan 24, 2002 2:20 pm|
|Sysop||Jan 24, 2002 2:22 pm|
|Sysop||Jan 24, 2002 2:24 pm|
|Bill Williamson||Jan 24, 2002 2:34 pm|
|Randy Lewis (Kenneth R. Lewis)||Jan 24, 2002 6:25 pm|
|Delyan Toshev||Jan 25, 2002 8:20 am|
|cap...@tomcat.colomsat.net.co||Jan 25, 2002 8:30 am|
|Randy Lewis (Kenneth R. Lewis)||Jan 25, 2002 8:57 am|
|Tomas Fasth||Jan 25, 2002 10:37 am|
|Johannes Erdfelt||Jan 25, 2002 10:40 am|
|Tomas Fasth||Jan 25, 2002 11:03 am|
|Sysop||Jan 25, 2002 12:20 pm|
|Sam Varshavchik||Jan 25, 2002 3:29 pm|
|Alessandro Vesely||Jan 26, 2002 7:34 am|
|Tomas Fasth||Jan 26, 2002 8:17 am|
|Sam Varshavchik||Jan 26, 2002 5:03 pm|
|Drew Raines||Jan 28, 2002 9:47 am|
|Subject:||[courier-users] Re: I.P. based (virtual) multiple Domains ...|
|From:||Alessandro Vesely (ves...@tana.it)|
|Date:||Jan 26, 2002 7:34:40 am|
Sorry answering with much delay, but I've been out and I'm surprised nobody answered correctly to this.
Bill Williamson wrote on Thu, 24 Jan 2002 15:19:14 -0600:
[...] When you connect to imap/pop3/smtp, you connect via IP address. That is all. If you look at the session, you never see "am I talking to mail.bubba.com?", just "here's my user and pass, let me in."
True the protocols don't specify the host name. However, the IP address the client connected to is known to the server. Hence, the server MAY behave differently when the request is received on a different IP address.
The reason you can do this with a web site is that in the http request header is the exact url that is typed in (servername and then file location).
That is true only for HTTP/1.1. In that case the protocol provides for a "Host" header with the host name. A server MAY then behave differently for different hosts EVEN IF they have the same IP address. It is what Apache calls "Name Based Virtual Hosts".
However, HTTP/1.0 and 0.9 clients are still being supported by many servers. And if you type the IP instead of the name you may still reach a page that depends on the IP address you used, even if the IP addreses are aliased (i.e. they refer to the same network interface) or if they correspond to the same host via different network interfaces. It is what Apache calls "IP-Based Virtual Hosts".
There is no way around this without making your own protocol, which nothing will support, except a client you make.
That's plainly wrong. Of course one can never get "Name Based" virtual hosts until the mail protocols won't support it, but Randy clearly stated that
If I have 10 aliased I.P. address on a machine, each DNS mapped to names like: mail.someplace.com mail.otherplace.com . . mail.yetanother.com
I'm lucky I don't have to waste IP addresses for easing users login. Courier does not support that option, but it allows to specify an IP address. Therefore, it should be possible to run multiple instances of Courier on the same machine and configure each instance to listen to only its IP address.
Of course, there is no need to differentiate SMTP servers. Only POP3 and IMAP need that, so there is space for optimizing the setup.
Actually, it is the couriertcpd program that listens on those ports, hence it sould be enough to provide the default server-name there. I would guess the problem can be solved by appropriate startup scripts and very minimal patches, if any.