Bind and Postfix

Friends.

Today, i configured bind dns and postfix mail server for my network.

dns works well i.e name resolves well.
the command host <hostname> gives proper answer.

But, the command dnsdomanname gives nothing.

The posfix works only with the server.
the port 25 is not visible from client systems.
but the mail sent for internal users works well.
the mail is is like this "(E-Mail Removed)"

so, i suspect the problem may be in dns.
how to get the dnsdomainname command work?

Thanks,
T.Shrinivasan.

On 2006-04-07, shrini <(E-Mail Removed)> wrote:
> But, the command dnsdomanname gives nothing.

dnsdomainname calls hostname to show the host name.

> The posfix works only with the server.
> the port 25 is not visible from client systems.

Something make me thing that you have a) a firewall blocking connection
from other systems to your smtp or b) postfix bind on 127.0.0.1 only.

Davide

--
A free society is one where it is safe to be unpopular.
-- Adlai Stevenson

Hi Davide.


> Something make me thing that you have a) a firewall blocking connection
> from other systems to your smtp or b) postfix bind on 127.0.0.1 only.



There is no firewall running.
i have given that "inet_interfaces=all"

How to check that it binds only on 127.0.0.1?
is there any way?

Thanks,
T.Shrinivasan.

On 6 Apr 2006 23:03:47 -0700, shrini <(E-Mail Removed)> wrote:
> Today, i configured bind dns and postfix mail server for my network.
>
> dns works well i.e name resolves well.
> the command host <hostname> gives proper answer.
> But, the command dnsdomanname gives nothing.

"hostname" should just show just your hostname, "hostname -f" should
show your full hostname.domain, and "hostname -d" should be just the
domain part (same as dnsdomainname).

> The posfix works only with the server.
> the port 25 is not visible from client systems.
> but the mail sent for internal users works well.
> the mail is is like this "(E-Mail Removed)"

"localhost" is always yourself (127.0.0.1 loopback). So you certainly
cannot mail from another PC to this PC using @localhost.localdomain in an
e-mail address. You need some other hostname (unique from other PC's in
your domain) which /etc/hosts and DNS should point to an IP on your box
(possibly ethernet nic IP if static), or when I was on dialup with no
static IP I assigned my hostname to another loopback IP 127.0.0.2.

To see what IPort postfix is listening on use "netstat -atn".
Local 0.0.0.0:25 means it is listening on port 25 of any interface. If
local is 127.0.0.1:25 that might be a default postfix setting for your own
safety. Check for inet_interfaces setting in postfix's main.cf (maybe at
/etc/postfix/main.cf).

Foreign 0.0.0.0:* means it accepts a connection from any IP and
port.

> so, i suspect the problem may be in dns.
> how to get the dnsdomainname command work?

That might be based on the hostname.domain in /etc/HOSTNAME (not sure, it
simply works for me). Just be aware that network scripts may set that
file during boot or when bringing up an interface, so you may need to look
for a HOSTNAME setting in network related scripts.

On Fri, 07 Apr 2006 21:15:06 -0700, shrini wrote:

> Hi Davide.
>
>
>> Something make me thing that you have a) a firewall blocking connection
>> from other systems to your smtp or b) postfix bind on 127.0.0.1 only.
>
>
>
> There is no firewall running.
> i have given that "inet_interfaces=all"
>
> How to check that it binds only on 127.0.0.1? is there any way?
>
> Thanks,
> T.Shrinivasan.

Any way to test if your mail server software only bind to 127.0.0.1 ?

Sure! you can use the netstat command. Usually located under /bin/netstat.
Netstat can show the connection that are open for use and the currently
opened connections.

The syntax would be

netstat -a -n -u -t -w


The switches :

-a show All port ready for connection(s)
-n no name resolution (DNS)
-u show UDP "connection(s)"
-t show TCP connection(s)
-w show raw connection(s)

And if you only want to filter for mail (SMTP) port,

netstat -a -n -u -t -w | grep :25



If I may, a word of caution...

Running an open SMTP server on the Internet without a firewall
need some Very careful configuration. Not doing so is a guarantee
that some spammers will find your server and use it to relay its
own spam instead of your mail.

That might be a problem to you :

1) the resources in disk use, CPU time and network use will all
be consummated by someone else.

2) Sending spam (or Forwarding it) is a good way to end up on a
black hole list. Once inserted on such a list, may other mail server
so configured will find that your server is to be ignored and
suddenly you will end up with a much less mail that you wish
and a lot more mail that you do not...

So take a good look at configuration and firewalling...

For firewall, an easy program to configure firewall rule
is FireStarter. It's an graphical front end that will
help you build your rules. It is is available at :
http://www.fs-security.com/



Well I hope it help.