Not listening on port 25?

[antgel]

Hi all,

We're having big problems. Our Exchange 5.5 SP4 server stopped accepting
mail. It's not visible to the outside world, but it receives mail from
another server that is.

I can't telnet to port 25 for starters. Although netstat -a swears that
there is listening on the smtp port.

So, I telnetted to localhost smtp (as in using the symbolic smtp name rather
than the number. Lo and behold, a banner.

How could this be happening? I thought the Internet Mail Connector (which
I've already reinstalled) would only listen on port 25. I wonder if W2K
thinks that SMTP means something else?

Here's a port scan. Any of these Exchange in disguise?

27/tcp open nsw-fe
80/tcp open http
110/tcp open pop-3
119/tcp open nntp
135/tcp open loc-srv
139/tcp open netbios-ssn
143/tcp open imap2
389/tcp open ldap
443/tcp open https
445/tcp open microsoft-ds
563/tcp open snews
593/tcp open http-rpc-epmap
636/tcp open ldapssl
993/tcp open imaps
995/tcp open pop3s
1029/tcp open ms-lsa
1031/tcp open iad2
3052/tcp open PowerChute
33
72/tcp open msdtc
6000/tcp open X11

Antony

 

[Rakesh Chanana [MSFT]]

Even though you said that netstat showed that Exchange was listening on
port 25, it didn't show up in the netstat output that you have there.
Exchange does listen on other ports such as 110 (for pop3) but receivning
emails is always on port 25.
When you were able to connect to localhost smtp, you connected to 127.0.0.1
port 25 and not the actual IP address assigned to the NIC of the exchange
machine.

Have you tried restarting exchange services to see if it starts listening
on port 25 again? Have you looked through the event logs to see if there
are any errors as to WHY exchange is not listening on port 25?
----
Thanks,
Rakesh Chanana [MSFT]

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--------------------

 

[Julie Norberg [MSFT]]

Hi Anthony,

I didn't see port 25 in your scan below but you may want to take a look at
this public KB article ID: 256590.KB.EN-US.

It states that the port the Internet Mail Connector (IMC) uses can be
changed by altering the Services file found in Winnt\System32\Drivers\etc.
If SMTP is assigned to 25/tcp then this file should be correct.

When you try to telnet into the IP address of the Exchange server, do you
connect at all? Meaning are you getting "Could not open a connection to
host on port 25 : Connect failed"?

Are you able to successfully telnet and connect into the Exchange server on
another port such as 110 and get a banner back? (not using the localhost IP
of the server)
- when trying to telnet, you may want to try this from another machine on
the same LAN as the Exchange server as well as from the server itself.
If you are not able to connect on other ports using the IP of the server
instead of the localhost, you may want to double-check that you are not
experiencing any network or NIC issues.

You may also want to double-check the IP address of the Exchange server by
performing an "ipconfig" at a command prompt to make sure that the IP
address is what it should be, making sure that it did not receive a new
address from a DHCP server or something like this. (Exchange servers should
have static IP addresses.)

What type of server do you have currently receiving all inbound mail on port
25 directly from the internet, is it a firewall? Are you able to telnet to
the internet IP address of this server and get a connection on port 25? Is
it queuing all the inbound mail destined for the IMC?

Are you having any trouble sending mail outbound from the IMC to the
internet?

Thanks,
Julie

--
Julie Norberg [MSFT]
(e-mail address removed)

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