Absolute SUSE Newbie - firewall rules
 

Personally I'm a *BSD user. But a client of mine has adopted me as their technician which includes administering their SuSE 7.0 server - firewall, mail and fileserver.

When I get the chance I have full intention of learning the SuSE operating system or moreso the packages it uses.

My immediate question is where I need to go and what I need to do in order to allow and forward the port traffic necessary for one of the client machines to accept a connectoin with Windows XP remote desktop sharing. I'm yet to know the port that this listens on but that shouldn't be hard to find. What I need to know is what file I need to edit to allow this to happen and how to forward the traffic to the correct machine. I have NO experience with SuSE. I didn't setup the server and what packages it is using are unknown to me. Is there any way I can find out what application they're using for mail (I believe it's fetchmail) and for their firewall?

So... in short

a) what do I have to do step by step to have this traffic enabled and forwarded?

b) how can I find out what package they're using for mail and firewall?

For what it's worth - I'm relatively accustomed to *BSD's pf - but I"m aware iptables is QUITE different.

I'm in the process of learning qmail.

I'm in a bit of a situation here guys and any help would be greatly appreciated.

Thanks in advance,
Gsee

Um, the later SuSE's (>=8.2) allow firewall administration via YAST. Did you try there? They should shepherd you through the rules and since you know BSD...

And then:

http://www.linuxguruz.com/iptables/ ;)

I don't know enough to write your IPTABLES rules, sorry.

From the boot-up infos SuSE is writing to your screen? (At least Postfix is started for internal mails (system -> admin) and probably SuSEfirewall).

I've been working with IPTABLES based firewalls for a few years now. Since you have a much older version of SuSE, it'll most likely be IPCHAINS. I'm not sure when they made the switch, but IPTABLES was adopted a few years back. If your kernel is in the 2.2.x tree, it'll be IPTABLES, as 2.4.x kernels are using IPCHAINS. If it's older than both of those, you'll want to look into ipfwadm. Either way, you'll want to look at http://www.netfilter.org/.

Thanks for your replies. I

The server is running the following:

SuSE Linux 7.0 (i386) Kernel 2.4.25

I understand that with SuSE not using anything like *BSD's pf it's not as easy as opening pf.conf and making a rule such as:

that would redirect all incoming connections to the router straight through to the $server when coming in on port $remoteDesk.

In what way is the equivalent achieved with SuSE's firewall solution?

Thanks again,

Gsee

Would it be possible to upgrade to a more modern SuSE version? You'd greatly benefit from security fixes, especially if you expect this thing to be a firewall.

I haven't been with this client long enough for him to allow me to update or change his server around that much. I'd love to switch to BSD as I know it so much better than SuSE (woulndn't be hard). That's not intended to start a flamewar against SuSE - but stick with what you know 'eh?

For now, the answer to your question

...no... Can you still please try and help me though?

Gsee

just to keep the thread accurate, the 2.2.x kernel uses IPCHAINS. The 2.4.x kernel uses IPTABLES.

Anyway, you'll want to find the path to iptables on your system, but running this will accomplish forwarding port 80 from the external interface to an internal ip on port 80:

$iptables -A PREROUTING -t nat -p tcp -d $extip --dport 80 -j DNAT --to $intip:80

Of course for consistency, you'll want to insert that line in whatever script is already calling an existing firewall (if you even have one running already).

iptables -L -v will tell you about currently active iptables rules in your kernel.