Thanks for the clarification. I understand what you said. So, I installed fresh 22.04 and 24.04 (without IP settting) then added just two line in ssh.socket.d as you mentioned in description. (confirmed that ssh.socket is active)
then tried to access them. 22.04 success. 24.04 failed. Thanks. -- You received this bug notification because you are a member of Debcrafters packages, which is subscribed to openssh in Ubuntu. https://bugs.launchpad.net/bugs/2111226 Title: [email protected] is still needed for hv_sock in Noble release Status in openssh package in Ubuntu: Fix Released Status in openssh source package in Jammy: Fix Released Status in openssh source package in Noble: In Progress Status in openssh source package in Oracular: Fix Released Status in openssh source package in Plucky: Fix Released Status in openssh source package in Questing: Fix Released Bug description: [Impact] On Ubuntu VMs running under Microsoft Hyper-V, users commonly rely on 'hv_sock' (Hyper-V socket) to enable seamless SSH access using the 'hvc.exe' tool on the Windows host. This works correctly on Ubuntu Jammy and earlier ( and Oracular and later with different mechanism ), but fails silently in Noble due to a missing '[email protected]' systemd unit. The failure is due to a combination of systemd and OpenSSH changes: * In older versions (e.g., Jammy with systemd 249), the '[email protected]' unit was relied upon for socket activation ('Accept=yes' mode) and the unit file exists. * With the Ubuntu Kinetic release, '[email protected]' was removed, and no template unit was shipped by default. * systemd introduced systemd-ssh-generator in version 256 checks [email protected] unit and openssh provides [email protected] unit. * Ubuntu Noble ships with systemd 255, which lacks this feature, resulting in the absence of [email protected]. * Debian has restored a static '[email protected]' template in recent OpenSSH packaging. Noble’s OpenSSH package currently lacks it. As a result, the typical 'ssh.socket' activation workflow fails on Noble, breaking compatibility for 'hv_sock' SSH access. This issue affects all Ubuntu series between Kinetic and Noble (inclusive) where: * systemd < 256 is used (no dynamic generator) * '[email protected]' has been removed But I think Noble only needs SRU for now since the others are EOL. Basically user should setup ssh.socket correctly to use hv_sock(e.g changing Accept=no to Accept=yes) but creating whole service file ([email protected]) might be different story since Jammy was working fine. [Test Case] 1. Launch a Noble VM on Hyper-V. 2. Ensure the 'hv_sock' kernel module is loaded: echo 'hv_sock' >> /etc/modules 3. Adding the socket conf for SSH to listen on vsock: # cat > /etc/systemd/system/ssh.socket.d/vsock.conf << EOF [Socket] ListenStream=vsock::22 EOF 4. Reload and reconfigure systemd units: systemctl disable ssh.service systemctl daemon-reload systemctl stop ssh.service systemctl enable ssh.socket systemctl start ssh.socket 5. Attempt to connect from the Hyper-V host: hvc ssh user@ubuntu-vm Expected Result: Connection succeeds and SSH login is presented. Actual Result: The connection hangs. No systemd unit is spawned due to missing '[email protected]'. [Where problems could occur] Adding a static '[email protected]' template unit, as done in Debian(although it is [email protected]), is unlikely to interfere with traditional SSH service setups (i.e., 'ssh.service'). The '@' template only activates in conjunction with 'Accept=yes' sockets and does not conflict with existing unit files. Also it was working in Jammy. [Other Info] * Debian commit restoring '[email protected]' https://salsa.debian.org/ssh-team/openssh/-/commit/eb25ab611967996a0d57b4ee565faa7de58b41f6 * systemd 256 adding 'systemd-ssh-generator' https://github.com/systemd/systemd/commit/0e3220684c6184a2f70396d991200ae207a25377 * OpenSSH in Ubuntu removed '[email protected]' in https://launchpadlibrarian.net/619116456/openssh_1%3A9.0p1-1_1%3A9.0p1-1ubuntu1.diff.gz during Kinetic development. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/2111226/+subscriptions -- Mailing list: https://launchpad.net/~debcrafters-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~debcrafters-packages More help : https://help.launchpad.net/ListHelp
