SSH connection lags within network

eam · 08-01-2004, 11:57 PM

I want to make this as clear as possible. There are three computers: A B C. A runs Linux and B+C run Windows or Linux. A and B are both in my network. C is an outside computer.

B has no problems with SSH to any other computer, except when I try connecting to A, it lags. Works fine, lets me type a few letters, stops for 10 seconds, lets me input again for a few seconds and happens again. I can't work like that...

C can SSH to A with no problems (tried serveral different computers with different ISP and OS).

So the problem must be between A and B, but I'm stumped. I know this is a wierd problem so any help at all would be great. This was the best place I could think of to ask for help... Thanks.

eam

osvaldomarques · 08-02-2004, 02:40 AM

Hi eam,
I know very little about ssh. But, did you try to set verbose to get a clue? "ssh -vvv" will give you a lot of info about what is happening on the connection. Also, you can look the logs of both systems. "tail -f /var/log/messages" in another session also may give you a hint.

minrich · 08-02-2004, 03:55 AM

I would be interested to know what distro and version is running on A, also what version of Windows is running on B?

I presume you are running Apache on A, and Samba server?

Have you tried running Ethereal to capture network traffic while SSH'ing from B to A?

eam · 08-02-2004, 10:17 AM

I tried doing ssh -vvv but it didnt output anything when the problem opened. I did get something from Ethereal. at 34 seconds the lagging started, here's what it said:

Code:

    34.033914   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    197 34.037314   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      Encrypted request packet len=20
    198 34.087184   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    199 34.091359   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      Encrypted request packet len=20
    200 34.205189   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    201 34.208298   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      Encrypted request packet len=20
    202 34.316007   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Client: Encrypted packet len=10
    203 34.320282   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      [TCP Retransmission] Encrypted request packet len=80
    204 34.611226   192.168.0.5           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Server: Encrypted packet len=10
    205 34.614221   c-67-165-13-113.client.comcast.net 192.168.0.4           SSHv1    [TCP Out-Of-Order] Server: Encrypted packet len=10
    206 34.614272   192.168.0.4           c-67-165-13-113.client.comcast.net TCP      [TCP Dup ACK 188#2] 4628 > 22 [ACK] Seq=1093 Ack=752 Win=16769 Len=0
    207 34.617207   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net TCP      4628 > 22 [ACK] Seq=320 Ack=216 Win=16769 Len=0
    208 35.102017   192.168.0.4           198.65.119.20         HTTP     GET /hc/9104606/?site=9104606&cmd=inPage&page=http%3A//www.kvms.com/kvm_switches/2_port_kvm_switches.asp&title=2%20Port%20KVM%20Switch%2C%202-Port%20KVM%20and%202%20Port%20KVM%20Switches&visitorStatus=INSITE_STATUS&activePlugin=none&pageWindowName=&id=5439550396&scriptVersion=1.0&d=1091458774363&referrer=http%3A//www.kvms.com/kvm_switches/kvm_switches.asp%3Fr%3Dggas HTTP/1.1
    209 35.120779   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Client: Encrypted packet len=10
    210 35.124133   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      [TCP Retransmission] Encrypted request packet len=80
    212 35.321951   192.168.0.4           198.65.119.20         TCP      3796 > http [ACK] Seq=2676 Ack=1406 Win=15506 Len=0
    214 35.523137   192.168.0.4           198.65.119.20         TCP      3796 > http [ACK] Seq=2676 Ack=1581 Win=15331 Len=0
    215 35.985995   192.168.0.5           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Server: Encrypted packet len=10
    216 35.988991   c-67-165-13-113.client.comcast.net 192.168.0.4           SSHv1    [TCP Out-Of-Order] Server: Encrypted packet len=10
    217 35.989041   192.168.0.4           c-67-165-13-113.client.comcast.net TCP      [TCP Dup ACK 188#3] 4628 > 22 [ACK] Seq=1093 Ack=752 Win=16769 Len=0
    218 35.991998   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net TCP      4628 > 22 [ACK] Seq=320 Ack=216 Win=16769 Len=0
    219 36.730282   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Client: Encrypted packet len=10
    220 36.733855   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      [TCP Retransmission] Encrypted request packet len=80
    221 38.735523   192.168.0.5           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Server: Encrypted packet len=10
    222 38.738535   c-67-165-13-113.client.comcast.net 192.168.0.4           SSHv1    [TCP Out-Of-Order] Server: Encrypted packet len=10
    223 38.738583   192.168.0.4           c-67-165-13-113.client.comcast.net TCP      [TCP Dup ACK 188#4] 4628 > 22 [ACK] Seq=1093 Ack=752 Win=16769 Len=0
    224 38.741530   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net TCP      4628 > 22 [ACK] Seq=320 Ack=216 Win=16769 Len=0
    228 39.949297   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Client: Encrypted packet len=10
    229 39.953374   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      [TCP Retransmission] Encrypted request packet len=80
    230 40.802718   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    231 40.806188   c-67-165-13-113.client.comcast.net c-67-165-13-113.client.comcast.net SSH      Encrypted request packet len=20
    232 41.741473   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    233 41.746028   c-67-165-13-113.client.comcast.net 192.168.0.5           SSHv1    [TCP Previous segment lost] Client: Encrypted packet len=10
    234 41.748043   192.168.0.5           c-67-165-13-113.client.comcast.net TCP      22 > 4628 [ACK] Seq=752 Ack=1013 Win=7504 Len=0 SLE=130256670 SRE=130256690
    235 41.751046   c-67-165-13-113.client.comcast.net 192.168.0.4           TCP      22 > 4628 [ACK] Seq=752 Ack=1013 Win=7504 Len=0 SLE=130256670 SRE=130256690
    236 42.098487   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    Client: Encrypted packet len=10
    237 42.102978   c-67-165-13-113.client.comcast.net 192.168.0.5           SSHv1    Client: Encrypted packet len=10
    238 42.104954   192.168.0.5           c-67-165-13-113.client.comcast.net TCP      [TCP Dup ACK 234#1] 22 > 4628 [ACK] Seq=752 Ack=1013 Win=7504 Len=0 SLE=130256670 SRE=130256710
    239 42.107963   c-67-165-13-113.client.comcast.net 192.168.0.4           TCP      [TCP Dup ACK 235#1] 22 > 4628 [ACK] Seq=752 Ack=1013 Win=7504 Len=0 SLE=130256670 SRE=130256710
    240 42.108017   192.168.0.4           c-67-165-13-113.client.comcast.net SSHv1    [TCP Retransmission] Client: Encrypted packet len=10

A has the *5 IP and B is *4. I'm not sure that that all means, but it's different than the output when things are working.

Here is the SSH version in case that helps:

OpenSSH_3.4p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f