On Sat, Apr 27, 2002, Eliran wrote about "Unknown Ports":
> I have just ran netstat and found out that these ports are open:
> 515, 6000, 113, 25
> there are others but only these are connectable and in State LISTEN
> (netstat --inet -an), the 25 port is the mail server postscript and
> I allowed it.

You probably mean "postfix", not postscript ;)
To see which process is listening on these ports, add a "-p" option to
netstat (and run it as root, this is important!). 

> Then what is port 515, 6000, 113 I thought 113 is some kind of another
> mail server (not to send mail, to receive mail) but its not that.
> 
> I have checked a list of ports but they were only trojans ports only.

Your linux installation probably includes a file /etc/services with a
list of ports useful on Linux machines. From my /etc/services:

auth            113/tcp         authentication tap ident
printer         515/tcp         spooler         # line printer spooler
x11             6000/tcp        X               # the X Window System

So you probably have an identd listening on port 113, lpd listening on
515 and X Windows listening on 6000 (this is your.machine:0.0). A
netstat -p (like I explained above) would show you that.


> After googling for "Port 515" I found out this is a printer daemon
> (lpd) and I dont want others to be able to connect to it, is there
> a way to block it so only 127.0.0.1 will able to connect to it ?
> (ipchains ?)

Yes.

Here's a simple rule (untested, so please test it) not allowing anything
from ppp0 (assuming you connect externally with a modem) to connect to these
ports:
ipchains -A input -i ppp0 --dport 515 -j DENY -l
ipchains -A input -i ppp0 --dport 6000:6063 -j DENY -l
ipchains -A input -i ppp0 --dport 113 -j DENY -l

(note that the last rule, barring ident, will sometime give you trouble if
you're trying to run a mail server or an IRC client on your machine, because
these things may insist that you run a responsive ident client).

What I actually do instead is to block all ports, except only a few which
I allow. But I'm really paranoid :)

> Googling for port 6000 tells me it is a remote X server, others
> can connect to it ?

Right...

> I also run an Identd application for IRC ident and that should be port 113.

So you already know the answers, so why ask? :)

> I need port 113 and 25 open, about the printer daemon... I need it to
..
> Port 25 is important for my mail, and I need it too.

Are you sure you need port 25 open? Why? Are you trying to run a mail
*server* on your machine?

> So what I don't need is port 25 and 113 , X server (is this xfs?) should

No, xfs is the X *font* server.

-- 
Nadav Har'El                        |     Saturday, Apr 27 2002, 15 Iyyar 5762
[EMAIL PROTECTED]             |-----------------------------------------
Phone: +972-53-245868, ICQ 13349191 |Preserve wildlife -- pickle a squirrel
http://nadav.harel.org.il           |today!

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