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- - port 113 (https://www.linuxquestions.org/questions/linux-enterprise-47/port-113-a-809164/)

Hi,

I am having a big issue now. Mails sent from our server to a particular server is going to port 113. In that server port 113 is blocked. since port 113 is managed by Ident service, I made sure that it is disabled on our server. I am wondering why our server is sending mails to port 113? We have set up to use smtp port 25. I don't remember specifying Ident or port 113 on its configuration or settings.

Still looking for the reason why our server is sending emails to port 113 instead of 110?

Hi -

Here's the likely reason:

Quote:

http://www.dslreports.com/faq/225

Port 113 is often left visible by firewalls since 113 is the IDENT port.

IDENT is used when you connect to mail servers, or to IRC servers, to find out "who" is using the service. With IDENT filtered, your ISP mail server (unlikely) or IRC server (likely) may refuse your request or take a long time to respond as it waits for a closed/open response.

It is possible to remove IDENTD as showing up as a port by reconfiguring your firewall to over-ride the default rules. As above, if IDENTD is filtered in this way, IRC and mail servers may not work properly.

You can also decide that IDENTD is safe, since just having it visible does not mean there is anything that can be exploited on your side, and live with the less than "perfect" results.

Consult your firewall's documentation to open the port, or your mail server's documentation to disable the need for "identd" (for example: "define(`confTO_IDENT',`0s')dnl").

'Hope that helps .. PSM

Hey! Thanks for throwing some light...I have disable need of ident by changing the response time to 0s as u suggested("define(`confTO_IDENT',`0s')dnl") but still our mails are sent to port 113. It is causing a big issue here...This issue is particular for a single IP(destination IP. Our server is trying to sent mail from different ports to destination IP's port 113. The destination IP can recieve mails from others but from us because of the port 113.

Hi -

Again, it's crucial that you check the documentation for your particular mail server. Different servers, different versions of the same server, and even the same server on different platforms have different syntax.

It's entirely possible that the example "confTO_IDENT" syntax I gave you is incorrect for your mail server.

However, whatever your server, there's certainly a configuration option to change the port. Maybe it's currently set to "113", and all you have to do is change it to "25" (or, better, to port "smtp").

Here's example syntax for "sendmail", config file "sendmail.cf":

Quote:

DAEMON_OPTIONS(`Port=113,Addr=127.0.0.1, Name=MTA')
<= change this from "113" to "smtp", and restart sendmail...