SSH “lag” in LAN on some machines, mixed distros





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I've had a strange problem with SSH connections inside my LAN for a few months. It only happens when I'm using my Windows 10 device to connect to a (barebone) linux machine.



When I connect to a SSH server it's like my input is only sent once every second. If I hold a key, it doesn't print anything for a second and after that second I see every keystroke I did during that time.



This is how it looks on the working servers:



This is how it looks on the ones with the issue:



Things I have tested/found out




  • Changing the "UseDNS" setting in /etc/sshd doesn't fix it

  • It happens with bash (and zsh) on Debian (OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r 26 Feb 2019) and Ash on Alpine Linux (OpenSSH_7.9p1, OpenSSL 1.1.1b 26 Feb 2019)

  • It doesn't happen on Alpine Linux OpenSSH_7.7p1, LibreSSL 2.7.4

  • It doesn't happen with every machine, just some (not depending on the distro)

  • resolv.conf is correct

  • Error happens with and without ClientAliveInterval (tested on client and server)

  • Pinging the devices is always fast (less than 1 ms) so it's only SSH

  • It also lags when I ssh from the linux subsystem on Windows 10 and with Putty and with MobaXterm

  • No problems when I connect from Linux instead of Windows


Does anyone have any clues or things I could try?
Thanks










share|improve this question





























    7















    I've had a strange problem with SSH connections inside my LAN for a few months. It only happens when I'm using my Windows 10 device to connect to a (barebone) linux machine.



    When I connect to a SSH server it's like my input is only sent once every second. If I hold a key, it doesn't print anything for a second and after that second I see every keystroke I did during that time.



    This is how it looks on the working servers:



    This is how it looks on the ones with the issue:



    Things I have tested/found out




    • Changing the "UseDNS" setting in /etc/sshd doesn't fix it

    • It happens with bash (and zsh) on Debian (OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r 26 Feb 2019) and Ash on Alpine Linux (OpenSSH_7.9p1, OpenSSL 1.1.1b 26 Feb 2019)

    • It doesn't happen on Alpine Linux OpenSSH_7.7p1, LibreSSL 2.7.4

    • It doesn't happen with every machine, just some (not depending on the distro)

    • resolv.conf is correct

    • Error happens with and without ClientAliveInterval (tested on client and server)

    • Pinging the devices is always fast (less than 1 ms) so it's only SSH

    • It also lags when I ssh from the linux subsystem on Windows 10 and with Putty and with MobaXterm

    • No problems when I connect from Linux instead of Windows


    Does anyone have any clues or things I could try?
    Thanks










    share|improve this question

























      7












      7








      7


      3






      I've had a strange problem with SSH connections inside my LAN for a few months. It only happens when I'm using my Windows 10 device to connect to a (barebone) linux machine.



      When I connect to a SSH server it's like my input is only sent once every second. If I hold a key, it doesn't print anything for a second and after that second I see every keystroke I did during that time.



      This is how it looks on the working servers:



      This is how it looks on the ones with the issue:



      Things I have tested/found out




      • Changing the "UseDNS" setting in /etc/sshd doesn't fix it

      • It happens with bash (and zsh) on Debian (OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r 26 Feb 2019) and Ash on Alpine Linux (OpenSSH_7.9p1, OpenSSL 1.1.1b 26 Feb 2019)

      • It doesn't happen on Alpine Linux OpenSSH_7.7p1, LibreSSL 2.7.4

      • It doesn't happen with every machine, just some (not depending on the distro)

      • resolv.conf is correct

      • Error happens with and without ClientAliveInterval (tested on client and server)

      • Pinging the devices is always fast (less than 1 ms) so it's only SSH

      • It also lags when I ssh from the linux subsystem on Windows 10 and with Putty and with MobaXterm

      • No problems when I connect from Linux instead of Windows


      Does anyone have any clues or things I could try?
      Thanks










      share|improve this question














      I've had a strange problem with SSH connections inside my LAN for a few months. It only happens when I'm using my Windows 10 device to connect to a (barebone) linux machine.



      When I connect to a SSH server it's like my input is only sent once every second. If I hold a key, it doesn't print anything for a second and after that second I see every keystroke I did during that time.



      This is how it looks on the working servers:



      This is how it looks on the ones with the issue:



      Things I have tested/found out




      • Changing the "UseDNS" setting in /etc/sshd doesn't fix it

      • It happens with bash (and zsh) on Debian (OpenSSH_7.4p1 Debian-10+deb9u6, OpenSSL 1.0.2r 26 Feb 2019) and Ash on Alpine Linux (OpenSSH_7.9p1, OpenSSL 1.1.1b 26 Feb 2019)

      • It doesn't happen on Alpine Linux OpenSSH_7.7p1, LibreSSL 2.7.4

      • It doesn't happen with every machine, just some (not depending on the distro)

      • resolv.conf is correct

      • Error happens with and without ClientAliveInterval (tested on client and server)

      • Pinging the devices is always fast (less than 1 ms) so it's only SSH

      • It also lags when I ssh from the linux subsystem on Windows 10 and with Putty and with MobaXterm

      • No problems when I connect from Linux instead of Windows


      Does anyone have any clues or things I could try?
      Thanks







      linux ssh windows-10 putty lag






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Apr 4 at 19:32









      ChristianChristian

      116417




      116417






















          1 Answer
          1






          active

          oldest

          votes


















          14














          Typically this is a sign of Nagle's algorithm, you can turn that socket option off.



          (I have seen similar TCP delays between Linux and Windows before in other cases as well. In one case it was caused by interactions between TCP Windows sizes and PSH (Push) flags which caused Windows to acknowledge late and/or retry.)






          share|improve this answer


























          • Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

            – Christian
            Apr 4 at 19:49











          • @Christian thanks for confirmation, I simplified my answer a bit

            – eckes
            Apr 4 at 20:04











          • @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

            – Carsten S
            Apr 5 at 9:22











          • @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

            – Christian
            Apr 5 at 12:47











          • Hm, indeed strange.

            – eckes
            Apr 5 at 17:12












          Your Answer








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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          14














          Typically this is a sign of Nagle's algorithm, you can turn that socket option off.



          (I have seen similar TCP delays between Linux and Windows before in other cases as well. In one case it was caused by interactions between TCP Windows sizes and PSH (Push) flags which caused Windows to acknowledge late and/or retry.)






          share|improve this answer


























          • Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

            – Christian
            Apr 4 at 19:49











          • @Christian thanks for confirmation, I simplified my answer a bit

            – eckes
            Apr 4 at 20:04











          • @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

            – Carsten S
            Apr 5 at 9:22











          • @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

            – Christian
            Apr 5 at 12:47











          • Hm, indeed strange.

            – eckes
            Apr 5 at 17:12
















          14














          Typically this is a sign of Nagle's algorithm, you can turn that socket option off.



          (I have seen similar TCP delays between Linux and Windows before in other cases as well. In one case it was caused by interactions between TCP Windows sizes and PSH (Push) flags which caused Windows to acknowledge late and/or retry.)






          share|improve this answer


























          • Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

            – Christian
            Apr 4 at 19:49











          • @Christian thanks for confirmation, I simplified my answer a bit

            – eckes
            Apr 4 at 20:04











          • @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

            – Carsten S
            Apr 5 at 9:22











          • @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

            – Christian
            Apr 5 at 12:47











          • Hm, indeed strange.

            – eckes
            Apr 5 at 17:12














          14












          14








          14







          Typically this is a sign of Nagle's algorithm, you can turn that socket option off.



          (I have seen similar TCP delays between Linux and Windows before in other cases as well. In one case it was caused by interactions between TCP Windows sizes and PSH (Push) flags which caused Windows to acknowledge late and/or retry.)






          share|improve this answer















          Typically this is a sign of Nagle's algorithm, you can turn that socket option off.



          (I have seen similar TCP delays between Linux and Windows before in other cases as well. In one case it was caused by interactions between TCP Windows sizes and PSH (Push) flags which caused Windows to acknowledge late and/or retry.)







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Apr 5 at 5:45









          Solomon Ucko

          1054




          1054










          answered Apr 4 at 19:45









          eckeseckes

          746617




          746617













          • Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

            – Christian
            Apr 4 at 19:49











          • @Christian thanks for confirmation, I simplified my answer a bit

            – eckes
            Apr 4 at 20:04











          • @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

            – Carsten S
            Apr 5 at 9:22











          • @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

            – Christian
            Apr 5 at 12:47











          • Hm, indeed strange.

            – eckes
            Apr 5 at 17:12



















          • Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

            – Christian
            Apr 4 at 19:49











          • @Christian thanks for confirmation, I simplified my answer a bit

            – eckes
            Apr 4 at 20:04











          • @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

            – Carsten S
            Apr 5 at 9:22











          • @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

            – Christian
            Apr 5 at 12:47











          • Hm, indeed strange.

            – eckes
            Apr 5 at 17:12

















          Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

          – Christian
          Apr 4 at 19:49





          Awesome, thanks for that quick fix! In the Putty settings I unchecked the "Disable Nagle's algorithm" checkbox (which seems to be ticked by default) and now it works!

          – Christian
          Apr 4 at 19:49













          @Christian thanks for confirmation, I simplified my answer a bit

          – eckes
          Apr 4 at 20:04





          @Christian thanks for confirmation, I simplified my answer a bit

          – eckes
          Apr 4 at 20:04













          @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

          – Carsten S
          Apr 5 at 9:22





          @Christian, I am confused. You enabled Nagle's algortihm, and now the characters do not come in larger packets? That seems the wrong way around to me, so maybe the answer before the edit was actually better.

          – Carsten S
          Apr 5 at 9:22













          @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

          – Christian
          Apr 5 at 12:47





          @CarstenS yes all I did was uncheck the "disable Nagle's algorithm" in Putty meaning I enabled it. But I think it's an older version of Putty so maybe the lable on the checkbox is wrong

          – Christian
          Apr 5 at 12:47













          Hm, indeed strange.

          – eckes
          Apr 5 at 17:12





          Hm, indeed strange.

          – eckes
          Apr 5 at 17:12


















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