Help Needed: My RHEL5 box suddenly stopped accepting e-mails
Bohdan Sydor
bohdan at harazd.net
Tue May 10 07:08:42 UTC 2011
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.
>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.
--
regards
Bohdan Sydor
www.sydor.net
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