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Re: Help Needed: My RHEL5 box suddenly stopped accepting e-mails



Hi Bohdan,


On Tue, May 10, 2011 at 12:08 AM, Bohdan Sydor <bohdan harazd net> wrote:

> On 05/10/2011 07:41 AM, Mun wrote:
>
> > Well, unfortunately my IT dept is claiming their network is fine--and
> > therefore the problem lies
> > either with my system, or is not worth their time to debug.  I am still
> > I went ahead and made the changes to the iptables logging as you
> suggested.
> >  When I use swaks to
> > send my machine email from an offsite system, I _do_ see messages show up
> in
> > my /var/log/messages
> > file showing some kind of interaction between the offsite system and my
> > system.  I don't know what is
> > being discussed between the systems, but the offsite system does finally
> > timeout in it's attemt to connect.
>
>
> Additionally, you can run from a linux box that is in any external
> network the following command:
>
> nmap -p 22,25 yourMachineNameOrIP
>
> The output should be similar to the this:
>
>  PORT    STATE SERVICE
> 22/tcp  open  ssh
> 25/tcp  open  smtp
>
> OR rather to that:
>
> PORT   STATE  SERVICE
> 22/tcp open   ssh
> 25/tcp closed smtp
>
>
> In the report you would see if ports tcp 22 and tcp 25 are remotely
> accessible on the mail system.
>

Here's what I get from the remote side:

PORT STATE SERVICE
22/tcp open ssh
25/tcp filtered smtp

I don't know what filters are in place; is there any way to get more
information
about the filters?



>
> >From the other side, run on your mail server that command:
>
> netstat -ntlp | egrep ':2(2|5)'
>
> If the output is like this below
>
> tcp        0      0 0.0.0.0:22              0.0.0.0:*
> LISTEN      1105/sshd
> tcp        0      0 0.0.0.0:25            0.0.0.0:*               LISTEN
>      1735/sendmail
>
> you've got a kind of evidence for your IT dept.
>

Here is what I get on my system:

tcp 0 0 127.0.0.1:2208 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN -
tcp 0 0 127.0.0.1:2207 0.0.0.0:* LISTEN -
tcp 0 0 :::22 :::* LISTEN -

Thanks very much for the continued assistance!

Regards,

-- 
Mun



>
> --
> regards
>
> Bohdan Sydor
> www.sydor.net
>
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