Telnet 25 port

[Carme Torca]

Hi,

I want to know if it's possible to deny telnet to the port 25 at one server that works as a sendmail relay.

Thank-you very much!
Carmen.

[Stefan Farrelly]

Easily done, either in /etc/inetd.conf on the server you want to disable it comment out the line telnet and then do an inetd -c
OR
setup the /var/adm/inetd.sec file to block telnet only for certain IP adresses. See man on inetd.sec

[Carme Torca]

Yes... oh sorry... I have not explain me corretly. I want to deny the access to the 25 port to anyone, and I want to make it in one server that its working that sendmail relay.

[Stefan Farrelly]

To stop sendmail relaying mail thru port 25 you can simply stop sendmail on the server in question; /sbin/init.d/sendmail stop

Or you can add an entry to /var/adm/inetd.sec to block port 25 traffic for any or all IP addresses.

[Animesh Chakraborty]

Hi,
Not sure what you want..
Can you block port 25 in firewall ?


Thanks
Animesh

[Carme Torca]

Hi,

No, its not a Firewall, its the mail server.
I can make a telnet to the 25 port and send a mail directly, without connect to the application....and I want to resolve it.

I don't want to deny telnets that use the 23 port, only to the 25 port, that its use the smtp. But I want (at the same time) that all the mail works corretly.

Thank-you

[Santosh Nair_1]

I don't believe there's a way to disable telneting to port 25 without disabling the ability to receive mail. But if you're looking to secure your mail server, look into using postfix or qmail instead of sendmail.

http://cr.yp.to/qmail.html
http://www.postfix.org

-Santosh

[Marcin Wicinski]

Hi,

You cannot disable telneting to selected port (25) with standard HPUX procedures. Only by a firewall.

Later,

[Joseph C. Denman]

Comment out port 25 of the /etc/services file. Then restart inetd

/usr/sbin/inetd -c

Hope this helps.

...jcd...

[Marcin Wicinski]

If you comment port 25 in /etc/servives, smtp protocol wont be available any more.