Thanks. The strace is indeed useful, although it doesn't get us all the way there. This is very strange! It appears that the network monitor is attempting to create a Unix socket in the middle of sending a USERAUTH_SUCCESS packet, which is peculiar to say the least.
This may take a few iterations. Could you please revert your changes to sandbox-seccomp-filter.c, and instead apply the attached patch? You can apply it with "patch -p1 </path/to/sshd-debug.patch", and then repeat exactly what you did before to build and install it; I then only need the strace, generated using the same procedure as before. What I'm trying to do here is to narrow down exactly where sshd is heading off to try to create a socket. ** Patch added: "sshd-debug.patch" https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1690485/+attachment/4996722/+files/sshd-debug.patch -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to openssh in Ubuntu. https://bugs.launchpad.net/bugs/1690485 Title: openssh-server SIGSYS with 'UsePrivilegeSeparation sandbox' Status in openssh package in Ubuntu: New Bug description: The 'sshd' process gets 'authentication failure' and refuses to allow any login. dmesg indicates that the problem is SIGSYS on a call to 'socket' (syscall #41, signal #31). On a hunch, I decided to test whether the problem is related to 'seccomp' and changed /etc/ssh/sshd_config from the default # UsePrivilegeSeparation sandbox to the former standard value UsePrivilegeSeparation yes and logins started to work again. Obviously, I'd like to have the additional protection that sandboxing would give me. ProblemType: Bug DistroRelease: Ubuntu 17.04 Package: openssh-server 1:7.4p1-10 ProcVersionSignature: Ubuntu 4.10.0-20.22-generic 4.10.8 Uname: Linux 4.10.0-20-generic x86_64 ApportVersion: 2.20.4-0ubuntu4 Architecture: amd64 CurrentDesktop: XFCE Date: Fri May 12 21:06:20 2017 InstallationDate: Installed on 2017-04-08 (35 days ago) InstallationMedia: SourcePackage: openssh UpgradeStatus: Upgraded to zesty on 2017-04-24 (19 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1690485/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp