On Wed, May 22, 2002 at 02:28:00PM +0100, John Horne wrote: > This will no doubt be dependant on the O/S, but is it really a random > numbered port, the first non-privileged port it knows is not in use, or does > the O/S have any other mechanism for selecting the port? Well, it really depends on the OS. :) Some OSs just use incremental ports (like Windows), others use random ports, and some or some patches for some OS try to use strong random algorithms with very good entropy...
> My problem is that given that a site has a firewall blocking specific > non-privileged ports (e.g. 2222) against all IP traffic (both as a source > port or a destination port), if a genuine site tries to e-mail them a > message and the sending host selects that port (2222) then the mail message > will not be sent. (snip) The problem is the firewall. The admins may have their reasons to block income traffic from port 2222 (your example), but what reason could they possibly have for blocking traffic from that port to a privileged port? In this case, port 25? You may be able to limit outgoing ports to a defined, accepted port, but as you have no control over the hosts sending mail to you, you can't work around the firewall. Have a word with the admins and have then or allow all incoming traffic to port 25 or to privileged ports. Regards -- Luciano Rocha, [EMAIL PROTECTED]
