Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
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I have noticed that my internet connection is flakey. I first noticed this using OpenSSH to connect to my linux machine (running SuSE 9.2), but the problem is not unique to SSH, nor is it isolated to attempt to connect TO my machine (connections FROM my machine are also affected). It is rare for any SSH connection to last more than a few minutes, and sometimes a connection lasts a mere second. Suffice to say, this is not conducive to productivity!
I have checked to make sure TCPKeepAlive is set to 'no' in my sshd_config file, but I don't think this is an SSH-only issue.
According to YaST, my firewall is configured to allow HTTP and SSH services, but nothing else.
A colleague in the same building (on the same network) has no network issues. He can run SSH for days at a time with no interruptions. The only differences between our situations are that he is running an earlier version of SuSE, and his machine plugs straight into the wall, whereas mine sits on a simple hub to which two Windows machines are also connected. My machine has a static IP, as does his.
Does anyone have any suggestions on how I can properly diagnose and fix this problem?
I doubt if it is the firewall rules but can you post the output from:
iptables -nL
It is possible that the hub or network card is malfunctioning, is there any chance that you can patch it in to another device?
Another useful test would be to connect your PC directly to another PC via a crossover cable and see if the problem persists - this could narrow down a hardware issue to one device.
I can't see anything obvious in those rules but like a lot of distro supplied firewalls they are very cryptic. If you are on a secure lan then you may want to try disabling it to see if it makes a difference:
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -F
Originally posted by david_ross If you are on a secure lan then you may want to try disabling it to see if it makes a difference
Hmm, there's a thought. My machine does reside inside a protected network, and the network administrators opened up port 22 to allow me to use SSH.
If I disable the firewall on my machine (which I can do directly through YaST with SuSE), will my machine face any considerable risks? Temporarily disabling the firewall to determine if the problem rests with the firewall -- that doesn't concern me. But if disabling the firewall fixes the problem, would it be dangerous to leave it disabled permanently?
If they are only allowing ssh into your machine then I wouldn't be too worried if you trust the other people on your LAN. Obviously you should continue to check that your ssh server is reasonably current and doesn't have any known exploits but that should be done regardless of whether you have a local firewall running or not.
If it does fix the problem then I wouldn't neccesarily not replace it. I would probably suggest using something simpler to manage though. Most of these firewalls seem fine when using a graphical tool to edit them but by the time you need to work out what is wrong they can be difficult to work with.
Well, opening up the firewall didn't fix the problem. I'm running a test to see if the connection if flakey when I boot into Windows instead of linux. If it's not, it will rule out a hardware problem.
It's a Broadcom adapter. SuSE 9.1 didn't have drivers for it (I tried everything, updating the kernel, you name it) so I had to install SuSE 9.2 to get a network connection.
The network card now works under 9.2, but sadly the connection is intermittent.
Broadcom support is known to be far from brilliant on linux. The best proof I can show is a picture of finegan, the resident LQ hardware junkie, outside broadcom's head office: http://clockwatching.net/~fin/images/fbc5-small.jpg
It may be worth checking what conditions the card is running under. Can you post the output from:
ethtool eth0
mii-tool -vv eth0
It may be worth changing the speed down to 10HD as opposed to 100FD. You can set it with:
ethtool -s eth0 speed 10 duplex half
This will need reset after each reboot but we can do that automatically if it helps the situation.
Quote:
Originally posted by TrulyTessa The second command wasn't reconized on my system. Any alternate way of getting SuSE linux to tell me what you seek to know?
Both commands produce similar information, I just wasn't sure which or if both were installed on SuSE by default.
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