FTP / SSH Connections timing out?

arlorn · #1 27th November 2006, 10:01 PM

Hello. I'm somewhat new to Fedora so forgive me for any ignorance... but I've installed, configured, and reinstalled and reconfigured Fedora 5 and 6 with every installation guide I could find, and yet I'm still having a problem with sftp/ssh connections. My server is up and running, and I can view a webpage through apache on request, every request... however, for some reason only a few requests from putty psftp / ssh from another computer go through, and after they do, they stop responding after about a minute (as though they timed out). The amount of time before timing out is completely variable, sometimes it'll be after I get my first command prompt... sometimes after I enter a few commands... but often it'll be before I even get a chance to enter my password (and as such, it'll leave me sitting with a blank screen forever after typing in my username). That computer can connect to any other server without difficulty, so I'm sure it's my configuration.

My question is where to begin? I've tried figuring out what could be going wrong for far too long, but I can't seem to find any good resource about this, and my reinstallations have gotten me nowhere. Is there an appropriate log file for this problem I could be checking?

Thanks so much for your time, and any help, whatsoever, is greatly appreciated!,
-Jess

arlorn · #2 27th November 2006, 10:18 PM

I still experience the same behavior after disabling SELinux, so I'm sure that's not a problem as well.

Thanks so much!,
-Jess

wesamel · #3 27th November 2006, 10:26 PM

I really don't know much about this particular topic, but I'll take a stab in the dark and suggest that you try disabling the firewall or opening the necessary ports.

Brian1 · #4 27th November 2006, 11:08 PM

If the port is not being blocked then I would say a configuration or maybe a routing problem. Here is a link on setting up ssh that is pretty good. http://www.suso.org/docs/shell/ssh.sdf

Brian

arlorn · #5 28th November 2006, 03:53 AM

Hmm... The link was very helpful. I don't know what I changed to get it to work, but the problem appears to be gone now. Thanks so much!
-Jess

dtop99 · #6 28th November 2006, 03:58 AM

I would try turning the firewall off completely if it happens again just to rule that out.
Also lots of people seem to be having issues with IPv6 being enabled, there are some good threads in the forum outlining disabling this, just in case that's caused an issue.

harper2.0 · #7 4th December 2006, 04:02 AM

Hi guys, new here. I'm running a test web server on FC5 using the latest version of apache. I have no problems logging in via ssh and sftp when the machine is freshly booted. But after a long period of time, the machine takes too much time to respond causing a time out. COuld it be a hardware issue? It's on 256 mb ram, I'm pretty sure my processor is ok at 3.02 ghz Intel Pentium.

Any help is appreciated, thanks!

arlorn · #8 4th December 2006, 09:19 PM

Not that I'm the best person to be responding to this, quite obviously, but my first guess would be that it's a hardware issue... yes. The 256m ram stands out to me as rather low... which could perhaps be used up by other applications. In my experience, you start hitting some weird application behavior when your ram starts getting low. My first move would be to identify how much ram you're using on startup, and then again when ssh times out... This should be a function of System Performance (I believe?). Also, I would personally take a shot in the dark and try connecting via ssh/sftp from the server itself to see if it's, perhaps, a different connection problem. You can run ssh/sftp from the terminal command line. Also, I'd try restarting your ssh/sftp server (which you can do in Services, which is under the Administration section), after it starts timing out, and then see if it that behavior continues.

If you do all of those, and still can't figure it out, posting those result may help to get someone else's input as well.

Best of Luck,
-Jess

harper2.0 · #9 4th December 2006, 11:48 PM

Hi Arlorn, thanks for the reply. When I checked the free ram on my machine it said that it has something like 3MB free. I'm not sure if I read that right since I'm pretty new to linux. Probably I'll post a screen cap later.

Thanks!

arlorn · #10 5th December 2006, 01:28 AM

3 MB is extremely low... that's almost 99% of your memory... are you sure? The System Monitor is in

Code:

System > Administration > System Monitor

then click on Resources at the top. The middle section entitled "Memory and Swap History" shows the amount of resources you're using. While you're at it, you might as well check your CPU at the top, but I doubt that's the problem since you'd notice it in performance. The category to the left, "Processes", shows how the RAM is being divided between each process so you can see if you have any memory hog. Anyway, the other two things I suggested are kindof important for debugging as well. Then again, you can stop listening to me as soon as anyone else decides to chime in *smile*.

Best of Luck,
-Jess

harper2.0 · #11 5th December 2006, 02:16 AM

Thanks for keeping company Jess,

checked it out now and it say 45% of ram is free. So now I hooked up on one terminal to access the test machine and via putty this is what i get...

total used free shared buffers cached
Mem: 223592 202600 20992 0 6800 91768
-/+ buffers/cache: 104032 119560
Swap: 458744 0 458744

and then i run another check...

total used free shared buffers cached
Mem: 223592 202660 20932 0 6820 91768
-/+ buffers/cache: 104072 119520
Swap: 458744 0 458744

and another...

total used free shared buffers cached
Mem: 223592 203624 19968 0 6840 92564
-/+ buffers/cache: 104220 119372
Swap: 458744 0 458744

as you can see...the free memory colum is gradually decreasing...

arlorn · #12 5th December 2006, 03:34 AM

How far apart are you issuing those commands? It's quite possible you have a memory leak somewhere... perhaps you're using some software which has a bug? Assuming your memory is in fact dwindling down to nothing, then yeah, that should be causing some pretty big problems. I would try removing everything non-essential from starting up with your system, restart, and see if the problem is still around. If it isn't, then I'd start up the programs in groups until I found the one that was causing the leak. ... If it is still around.... then I'm not sure. I'm also afraid I'm not a great person to be asking about this, since, though I've used linux for quite a while, I haven't actually administered my own server until very recently. My best advice would be to post another topic with a catchy name in hopes to get someone a little more experienced to help diagnose that problem.

My apologies for not being more helpful, but best of luck!,
-Jess

andekhi_ti · #13 7th December 2006, 03:30 AM

you can optimize your linux performance maybe by :
disabling uneeded services, if your pc for server maybe it wouldbe more secure if you just using init 3 without X window.

or if you have extra hardisk you can make another swapfile or swappartition

dd if=/dev/zero of=swapfile bs=1024 count=512000
mkswap swapfile
edit fstap
swapon -a

for easy way u just upgrade your RAM

thanks