[LUAU] help on port 25

Eric Hattemer hattenator at imapmail.org
Fri Nov 9 11:05:06 PST 2007


Clifton Royston wrote:
> On Fri, Nov 09, 2007 at 12:27:12AM -0800, goku ball z wrote:
>   
>> hay guys..... I have a funny problem and I just can't figure out.  
>>   I just installed open suse 10.2 
>>   here is my problem on the suse box to test to see if port 25 is working i did the following
>>    
>>   telnet localhost 25   and it worked BUT..... when I did the following 
>>    
>>   telnet domain.com 25  I got connection refused.    
>>    
>>   I check the services, dns and everything I can think of.... can someone point me in the right direction?
>>     
A few more notes.  Try `iptables -L` and see if there are any iptables
rules that might specify port 25.  I still recommend a program called
fwbuilder if you're not familiar with iptables.  Or if you want to be
defenseless, on FC you can do `service iptables stop`.  I'm sure there's
something similar on suse.

Depending on how your routing works, it is possible that you are going
out to your ISP before you go back to your own IP address.  Many
intelligent home ISP's block and filter port 25 on their network to help
oppress the massive spam bots.  Unless you have a commercial server-type
agreement, it is unlikely that you will be able to have port 25 open,
deliver mail, and not have your outgoing mail marked as spam.  Often to
use another ISP's smtp server, you need to configure your mail client to
use port 465 or 587.  Many domains block all mail from dynamic or "home
user" IP addresses.  You might try configuring your MTA to bind only to
port 587 and only accept authenticated smtp if you want to use it as a
local SMTP server.  If you actually want to collect mail on that box,
but your ISP doesn't want you to, you're pretty much screwed.

But Clifton is probably right that if you didn't do enough configuring
on your MTA, you probably just missed the part where you open it up to
the public.  If you're using sendmail, don't.  The only reason to use
sendmail is to put it on your resume for those companies that are stuck
with it.  The configuration belongs back in the early 70's.  Even then,
they probably could have written a better configuration file, but
didn't.  Postfix is excellent and easy to setup.  I haven't looked into
qmail, but anything is better than sendmail.

-Eric Hattemer






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