Re: how to tell a socket to use a specific interface...
Re: how to tell a socket to use a specific interface...
- Subject: Re: how to tell a socket to use a specific interface...
- From: Eric Dahlman <email@hidden>
- Date: Sun, 22 May 2005 18:58:24 -0500
On May 22, 2005, at 1:51 PM, Justin Walker wrote:
There's relatively little that a bind() can do to make a remote
server happy. Unless you have something in mind that I don't
understand (Nah...), the only real reason to call bind() on a
socket that you will call connect() on is to deal with the
possibility that routing is not enabled on your system, and you
have multiple interfaces to choose from.
In this one case, you would want to bind to an address associated
to an interface that is "in the direction" of your destination.
Given the complex routing setups that could occur (adding a lot of
host routes, for example :-}), this could be necessary to overcome
bad decisions in the routing engine.
Other opinions solicited...
Just one crusty old example for historical correctness. Back in the
day some protocols (was it for zone transfers in the old DNS bind or
some such thing, I don't remember myself) would distinguish a
connection from a specific low numbered port from a high numbered
port. It was a little added protection since a normal user could not
use a low numbered port for outgoing traffic. Now in this day and
age that is just silly but those were simpler times...
-Eric
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