On Sat, 2005-08-27 at 00:11 -0500, Jonathan Berry wrote: > Hey everyone, > > Okay, a lot of ISPs now block port 25 out to anything other than their > SMTP server. In some situations, it would be nice to circumvent this > to get to another SMTP server if one is not available. So what I had > though is to setup my FC4 linux box to listen for SMTP traffic on a > non-standard port. Actually, I could just have my hardware router > forward whatever port to 25 on the computer, so the non-standard port > part should be easy. It would be nice to have a workable solution > with as little as possible. Does anyone know of some way that I could > maybe take any traffic to my server on my chosen high port and forward > it along to my ISP's SMTP server on port 25? It sounds possible, but > sketchy enough to where it might not be. Any ideas? I figure I could > always just setup my own SMTP server and that should work. But I > would need to make sure I did that right as I do not want to aid in > the spread of spam and/or viruses. Since it would be on a strange > port, it shouldn't be as big a problem, if at all. Any ideas on that > point? So, what do you think of my idea and options? If I were to go > the route of setting up my own SMTP server (perhaps even so far as a > whole email server) any tips as to where to start looking for info on > doing this right? ---- There's often no reason to do what you are speaking of. You can set Postfix or Sendmail to use your ISP's smtp server as a 'smart host' so outbound email will be delivered. Then other computers can use the system running Postfix or Sendmail delivering via the smart host can send mail. The only issue is computers that aren't on your local lan can't use your mail server to relay mail - which stands to reason. If for some reason you really believe you need to do what you are asking, the following is offered in sendmail.mc (and I presume something similar is configurable for postfix) dnl # The following causes sendmail to additionally listen to port 465, but dnl # starting immediately in TLS mode upon connecting. Port 25 or 587 followed dnl # by STARTTLS is preferred, but roaming clients using Outlook Express can't dnl # do STARTTLS on ports other than 25. Mozilla Mail can ONLY use STARTTLS dnl # and doesn't support the deprecated smtps; Evolution <1.1.1 uses smtps dnl # when SSL is enabled-- STARTTLS support is available in version 1.1.1. dnl # dnl # For this to work your OpenSSL certificates must be configured. dnl # dnl DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl and at this point - the ISP's blocking ports 25, 80, 137-139, 445 are not blocking 587 Craig
