Routing Problem Has Me Stumped

Hi!

I have run into a strange networking problem, and I've been fighting with it for the last 2 days without success, before turning to this forum for help.
I want to set up an Internet gateway / Samba server box for my home LAN. The weird thing is, this was already working before, and now it isn't, for reasons totally unclear to me. I'll lay it out from the beginning, step by step, trying to include all (and only) relevant info.
If that matters, all configuration was done through Yast, because I'm not that good yet

Here goes:

I installed openSuSE 10.3 on the server machine It has two integrated network interfaces, SUSE recognized them both, no problems there.
I set the external interface to use DHCP, the internal to a 192.168.1.0 range address.
DHCP server on the internal interface: gateway = suse internal interface IP, ISPs DNS server IPs hardcoded into the DHCP settings for simplicity (it won't change anyway)
Then I set up SUSEfirewall: external and internal interfaces set, all ports open on internal, all ports closed on external. asquerading is enabled.
I enadled IP forwarding in the routing section.
I set up Samba. I won't go into much detail here; security is not an issue, so there's a single user explicitly for the SMB clients to use, it owns all shared directories and files, and a Samba password is set for it.

At this time, the client machines (all of them Windows) have internet access. They can browse the SMB shares, access them with the proper password. Reading/writing the shares is OK. Everything works perfectly.

Then, I decided to try a few router distributions, mainly for their HTTP management interfaces. My "end users" (family) are not too rich in the linux knowledge department. I tried ClarkConnect and eBox, but they didn't work out too well, probably because of my ignorance (I'm a little lost without Yast myself).

So I think, back to SUSE it is. I follow the SAME steps I outlined above... And I have problems. I will try to describe the symptoms as best as I can:
My link tio the ISP is OK: the SUSE machine can do everything. Ping, HTTP, FTP all works fine. (didn't see the need to test other stuff)
DHCP server is still good: my clients get a LAN address, parameters are correct.
ICMP packets seem to be routed correctly: name resolution and ping works from the LAN. (ping google.com is successful)
Web browsing on the LAN does not work: the server name gets resolved, the request is sent, and the browser is waiting for a response forever (well, until it timouts).
Samba server is visible to the clients. They can list the shares. When I try to acces a share from them, it's the same thing, waiting until timeout.

At first I thought I screwed up the firewall settings and TCP packets are dropped on the internal interface. But I double- and triple-checked everything (and tetra- and penta- and so on...), and it should be fine. Plus, the SMB shares are listed correctly on the clients, so there IS TCP traffic.

I've reinstalled SUSE like 6 times in the last 2 days trying to amke it work from a clean system. I'm nearing the end of my sanity here. What am I doing wrong? Please help!

I've been digging around a little in /var/log/messages, and noticed a couple of socket errors every time a client tries to access a Samba share.

Feb 23 12:02:01 147-121-16-213 smbd[4567]: [2008/02/23 12:02:01, 0] lib/util_sock.c:get_peer_addr(1232)
Feb 23 12:02:01 147-121-16-213 smbd[4567]: getpeername failed. Error was Transport endpoint is not connected
Feb 23 12:02:01 147-121-16-213 smbd[6590]: [2008/02/23 12:02:01, 0] lib/util_sock.c:get_peer_addr(1232)
Feb 23 12:02:01 147-121-16-213 smbd[6590]: getpeername failed. Error was Transport endpoint is not connected
Feb 23 12:02:01 147-121-16-213 smbd[6590]: [2008/02/23 12:02:01, 0] lib/util_sock.c:write_data(562)
Feb 23 12:02:01 147-121-16-213 smbd[6590]: write_data: write failure in writing to client 0.0.0.0. Error Connection reset by peer
Feb 23 12:02:01 147-121-16-213 smbd[6590]: [2008/02/23 12:02:01, 0] lib/util_sock.c:send_smb(769)
Feb 23 12:02:01 147-121-16-213 smbd[6590]: Error writing 4 bytes to client. -1. (Connection reset by peer)

Also, smartd gives a large number of "UDMA_CRC_error_count changed" messages for the HDD mt root partition is on. It's a fairly old PATA drive, it's not unconcievable that it's slowly dying. Yet, the system boots up normally every time. Can a bad HDD be the culprit?

Welcome to the forum, wrajk!

While I do not have an exact answer to your question, I do have a link you may wish to try: http://www.swerdna.net.au/ . This is an excellent resource set up by Swerdna. He knows networking! There are several tutorials and links on his site. You might find your answer with him.

There are plenty of knowledgeable and experienced openSUSE users in this forum, so chances are you can find you answers soon enough, if you still need assistance. With everyone spread out all over the world, folks are signing in and out of the forum all the time. It might take a few minutes or a few hours, so please be patient. You will find our community to be very friendly and willing to help you out as much as possible. We are glad to have you with us.

It can usually be beneficial if you could post some hardware/software specifications, since there are several versions of openSUSE, as well as different desktop environments. That would help point folks in the right direction to help solve your issue. Posting the log files was a good idea. I know others must have had a similar issue.

Good luck, and please post back with your results.

Thanks for the welcome! Judging from your reply this is a friendly forum indeed. And thanks for the link too, I've found some useful articles in there.

I really want to tackle this one, and I'm prepared to wait for the wisdom of the group. As a matter of fact, I've come up with a backup plan until the solution is found, and now that my family isn't breathing down my neck to "get us some Internetz RIGHT NOW" I'm feeling pretty Zen about it all.

As for some background, I'm using the openSUSE 10.3 i386 DVD to install. The machine is my former desktop, which I've decided to put to good use instead of letting it catch dust in a drawer. It's an AthlonXP 3000+ (Barton core) with 2GB RAM, the motherboard is some flavor of MSI K7N2 or other, and an ATI X800 video card (can't remember the exact model either)
Seems a bit of an overkill for a router, but I'm planning to make it a fileserver too (hence the Samba), which will involve me buying some extra SATA controllers, filling the case to the brim with ****loads of HDDs, put them in a RAID-5 MD array and enjoy. I already mentioned the internal network interface is gigabit ethernet, and I seem to recall hearing MD eats up CPU time nicely, so maybe all that power won't be wasted after all.

Hope that helps. If you guys need any more information, or logs, or whatever, I'll be happy to provide it.