UNIX for Dummies Questions & Answers

how can i check to see if my mail ports are open (port 110 for incoming and 25 for outgoing)? I want to do this because i am having a problem sending email out. If one of the ports has a problem, how can i open it? Thanks in advance!

Try telneting to those ports and see if you get any responses. If the daemons are there, you should get some kind of response.

how do you do it? is it xxx.xxx.xxx.xxx:25

Try

netstat -a | more

ur gonna see all the ports on your host,
those ones with LISTENT are currently with open connection and waiting for client to connect. ESTABLISHED then connection is established. Do "man netstat", you're gonna get lots of useful info.

Regards

djatwork has raised a very interesting problem here. Is it true that you need port 110(POP3) to be open for sending email out ??
I can send email out fine but when I check my port 110 is not open. The problem I have is that I can not receive email at all or can not send email locally (between my users).

Here is what I get using the netstat command :

<pre>

% netstat -a |grep 25
*.1225 Idle
isgsi01.32925 isgsi01.32917 32768 0 32768 0 ESTABLISHED
isgsi01.32917 isgsi01.32925 32768 0 32768 0 ESTABLISHED

% netstat -a |grep 110
isgsi01.1521 10.153.6.198.1108 16210 0 8760 0 ESTABLISHED

% netstat -a |grep mail
%
I get nothing here.

</pre>

It seems like I get nothing relevant here about ports 25 and 110. I still can send email out to the outside world, any ideas at all please guys?

Also trying the 'newaliases' command I get :

<pre>

% newaliases
WARNING: World writable directory /var
WARNING: World writable directory /etc
dbm map "Alias0": unsafe map file /etc/mail/aliases: No such file or directory
Cannot create database for alias file /etc/mail/aliases

</pre>

Anyone played around with sendmail before?

Any help will be appreciated.
Thanks

No, you do not need port 110 "open" to send mail. If you are operating a POP3 server process normally listens on port 110. However, you do not need a POP3 server to send mail.

You do not need port 25 "open" to send mail. If you are receiving mail an SMTP server process normally listens on port 25. However, you do not need an SMTP listening process to send mail (only receive).

uhm... that's not good...
You (or your admin) should change that. Since Unix will check the directory permissions first, it may be possible for you to clobber a file... example:
( I almost put in something to do with /etc/passwd or /etc/shadow, but decided against it... don't want to contribute TOO much to delinquency...)

Code:

$ cd /etc
$ cat > resolv.conf.me
#Haha! I'm so evul! Now you can't resolve anything!
^D
$ mv resolv.conf.me resolv.conf

Like I said above, anything in /etc or /var can be overwritten... That's bad news.