Odd Problem - Connecting to SMTP

Odd Problem - Connecting to SMTP

[Chris Shipman]

    I have a strange problem.      When I try to connect to a mail server from my linux router it can't connected to port 25.   It seems like only port 25 is affected.
The WAN port is DHCP and the LAN is set static with NAT enabled on outbound.

    However a computer behind my linux router has no trouble connecting to port 25.    It's only when I try to connect from the linux router itself.   I'm using IPTables 1.3.3

    Does anyone have an idea of what is causing this?

Regards,


Chris

Re: Odd Problem - Connecting to SMTP

[Yaman Saqqa]

Can you post your ruleset .. INPUT/OUTPUT at least ?

On 9/4/05, Chris Shipman <listmail@odisok.net> wrote:
>     I have a strange problem.      When I try to connect to a mail server from my linux router it can't connected to port 25.   It seems like only port 25 is affected.
> The WAN port is DHCP and the LAN is set static with NAT enabled on outbound.
> 
>     However a computer behind my linux router has no trouble connecting to port 25.    It's only when I try to connect from the linux router itself.   I'm using IPTables 1.3.3
> 
>     Does anyone have an idea of what is causing this?
> 
> Regards,
> 
> 
> Chris
> 


-- 
abulyomon

www.KiLLTHeUPLiNK.com

Re: Odd Problem - Connecting to SMTP

[/dev/rob0]

On Sunday 2005-September-04 13:49, Chris Shipman wrote:
>     I have a strange problem.      When I try to connect to a mail
> server from my linux router it can't connected to port 25.   It seems
> like only port 25 is affected. The WAN port is DHCP and the LAN is
> set static with NAT enabled on outbound.

Many ISP's do block outbound SMTP for dynamic IP space because of the 
prevalence of Windows spam worms. But ...

>     However a computer behind my linux router has no trouble
> connecting to port 25.    It's only when I try to connect from the
> linux router itself.   I'm using IPTables 1.3.3

... this appears to refute that hypothesis in this case.

>     Does anyone have an idea of what is causing this?

Perhaps you have an OUTPUT rule which you did not understand.
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    mail to this address is discarded unless "/dev/rob0"
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Re: Odd Problem - Connecting to SMTP

[R. DuFresne]

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On Sun, 4 Sep 2005, Chris Shipman wrote:

>    I have a strange problem.      When I try to connect to a mail server from my linux router it can't connected to port 25.   It seems like only port 25 is affected.
> The WAN port is DHCP and the LAN is set static with NAT enabled on outbound.
>
>    However a computer behind my linux router has no trouble connecting to port 25.    It's only when I try to connect from the linux router itself.   I'm using IPTables 1.3.3
>
>    Does anyone have an idea of what is causing this?
>


some linux dists also compile tcpd/sendmail to work and play together, and 
this might be the case if your setup has a default deny in the 
/etc/hosts.deny file, took awhile to figger that out here when working 
with a new slackware setup and old hosts.xxx files moved from other 
working setups.

Thanks,

Ron DuFresne
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