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Old 04-12-2005, 03:12 AM   #1
Registered: Dec 2002
Location: algeria
Distribution: redhat 7.3, debian lenny
Posts: 622

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port 25 is closed?

Hi, I just installed the CentOS4.0, (redhat Entreprise based) .
I installed the smail server postfix, configured,
when I test telnet 25, the remote machine doesn't reply ( access refused ) ???
I tried manually the /usr/libexec/postfix/smtpd -D, it failed ,with message , not running by hand
There is no /usr/sbin/smtpd ( maybe it has another name or in another place ???) as in mandrake for example ?

the port 110 ran correcly
telnet server 110 gives the login

please someone can help me, pointing me what are the required soft to run correctly the postfix server

best regards
Old 04-12-2005, 05:49 AM   #2
Registered: Dec 2001
Location: Portugal
Distribution: /Red Hat/Fedora/Solaris
Posts: 622

Rep: Reputation: 30

I hope I understood the quetion correctly. Are u telneting to the mail server from the remote box and if yes then u have to enable that port 25 on the FW where the mail server is installed. The easiest way to test this before configuring iptables disable it first then test the telnet connection. To disable FW type service iptables stop. If u not familiar with iptables use redhat-config-securitylevel and configure port 25 to be accessed

Old 04-12-2005, 12:05 PM   #3
Registered: Dec 2002
Location: algeria
Distribution: redhat 7.3, debian lenny
Posts: 622

Original Poster
Rep: Reputation: 31
but I flushed the iptables and after that I stopped it .
the problem is that sometimes it works and sometimes not, so there is probably a daemon who stops the access

For example I noticed in mandrake 9.0 ( i think, don't really remember the release) /usr/sbin/smtpd with permission only for root, and I fixed the problem by running by hand the smtpd as daemon with -D option.
here there is no smtpd at all !!!!

thanks for replies
best regards
Old 04-12-2005, 03:58 PM   #4
Registered: Apr 2005
Location: Texas
Distribution: RHEL 2.1,3.0,4.0
Posts: 39

Rep: Reputation: 15
A default install of Postfix (or Sendmail) on CentOS 4.0 or RHEL will only be listening on the loopback interface. I think this is a precautionary measure to keep folks from exploiting you as a spam relay or whatever. The fewer open ports, the better.

You can check which interfaces are listening with the following command

# lsof -ni
sshd 3420 root 3u IPv6 7408 TCP *:ssh (LISTEN)
sendmail 3450 root 4u IPv4 7498 TCP (LISTEN)

in the above example, ssh is listening on all interfaces & sendmail is only listening on the loopback interface.

You can also use the "netstat -l" command to see similar output.

At any rate, you need to edit the Postfix config file to tell it to listen on an interface besides the loopback.



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