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I have a quite strange problem regarding the connecting to a remote server.

The problem is very annoying when I'm using Midnight Commander (mc), just to scroll or inside the editor.

Overall there is a big lag between when I press a key and I get the response.

Now here is the current list of investigations:

Network speed

26 packets transmitted, 26 received, 0% packet loss, time 25033ms
rtt min/avg/max/mdev = 154.538/158.928/178.473/5.057 ms


I tried to transfer a 50MB zip file from my machine to the server via SSH(scp) and I got an average speed of >1Mbps (initially the speed was around ~150kbps but grew fast)

Machine load

top - 02:36:09 up 217 days, 5 min,  3 users,  load average: 0.22, 0.55, 0.40
Tasks:  75 total,   2 running,  73 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni,100.0%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   2053312k total,  1940624k used,   112688k free,    22848k buffers
Swap:   392184k total,    12556k used,   379628k free,   742936k cached

Note: this is a virtual machine and I asked IT if there is load issue with the guest and they reported that everything is ok.

What else could cause this and how to solve it?

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Can you sniff your ssh traffic when using mc? If there's lots of tcp packet loss/retransmit - it will show you that problem is with network congestion. –  DukeLion May 18 '12 at 11:02

1 Answer 1

The same happend with my installation after core sysctl fine tuning. I'll try to find out, what is particular parameter I've changed and post my "research" here.

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The problem was not in sysctl fine tuning (in my case). I've checked my iptables rules and find ugliest loops. After iptables rule revisioning and rewriting everything is fine now. Loops can make degradation of internal connection speed and this can be a solution you are looking for. –  Daniel Oct 22 '12 at 3:52

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