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





























    2















    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

























      2












      2








      2








      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











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      asked 8 hours ago









      ChristianChristian

      88416




      88416






















          1 Answer
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          6














          Typically this is a sign of Nagel’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


























          • 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
            8 hours ago











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

            – eckes
            8 hours ago












          Your Answer








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          1 Answer
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          active

          oldest

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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          6














          Typically this is a sign of Nagel’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


























          • 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
            8 hours ago











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

            – eckes
            8 hours ago
















          6














          Typically this is a sign of Nagel’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


























          • 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
            8 hours ago











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

            – eckes
            8 hours ago














          6












          6








          6







          Typically this is a sign of Nagel’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















          Typically this is a sign of Nagel’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













          share


          share








          edited 8 hours ago

























          answered 8 hours ago









          eckeseckes

          656516




          656516













          • 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
            8 hours ago











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

            – eckes
            8 hours ago



















          • 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
            8 hours ago











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

            – eckes
            8 hours ago

















          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
          8 hours ago





          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
          8 hours ago













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

          – eckes
          8 hours ago





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

          – eckes
          8 hours ago


















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