Public bug reported: After upgrading to 25.10, ssh no longer connects to my known servers with RSA or ECDSA keys.
Running ssh -vvvv 192.168.1.21 (to connect to a server in my home network) I see the following last few lines (I've "sanitized" a few of the lines with ***): ebug2: pubkey_prepare: done debug1: Offering public key: /home/***/.ssh/id_rsa RSA SHA256:+w3pYL8L+***+uPA agent debug3: send packet: type 50 debug2: we sent a publickey packet, wait for reply debug3: receive packet: type 60 debug1: Server accepts key: /home/***/.ssh/id_rsa RSA SHA256:+w3pYL8L+***+uPA agent debug3: sign_and_send_pubkey: using [email protected] with RSA SHA256:+w3pYL8L+***+uPA debug3: sign_and_send_pubkey: signing using rsa-sha2-512 SHA256:+***+uPA And at this point, nothing... I found this useful article on setting up ssh on Ubuntu 25.10: www.ezone.co.uk/blog/enabling-ssh-and-key-based-login-in- ubuntu-25-10.html which suggests, without much more detail, the use of ED25519 keys. So I used ssh-keygen to generate an ED25519 pair and put the public key on the server "by other than ssh means"; and then I was able to connect. The debug output given with ssh -v 192.168.1.21 now shows first offering the ED25519 key, and after the offering stanza, the server accepts stanza. I should point out that I have the same issue connecting to my small home network Debian IOT devices and to an Ubuntu 22.04 server out in the cloud - same "off in the weeds" behaviour from the ssh client until I get an ED25519 pair in place. I should also emphasize that I don't have a problem moving to a newer, better key technology; it's the ssh client sitting there waiting for something behaviour that's the problem. I don't think this bug is a security vulnerability, but it could lead to people falling back to password authentication for ssh connections, which would be a security vulnerability. ProblemType: Bug DistroRelease: Ubuntu 25.10 Package: openssh-client 1:10.0p1-5ubuntu5 ProcVersionSignature: Ubuntu 6.17.0-6.6-generic 6.17.1 Uname: Linux 6.17.0-6-generic x86_64 ApportVersion: 2.33.1-0ubuntu3 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Fri Oct 31 10:06:24 2025 InstallationDate: Installed on 2024-04-27 (552 days ago) InstallationMedia: Ubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240424) RelatedPackageVersions: ssh-askpass N/A libpam-ssh N/A keychain N/A ssh-askpass-gnome N/A SSHClientVersion: OpenSSH_10.0p2 Ubuntu-5ubuntu5, OpenSSL 3.5.3 16 Sep 2025 SourcePackage: openssh UpgradeStatus: Upgraded to questing on 2025-10-30 (1 days ago) ** Affects: openssh (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug questing wayland-session -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2130448 Title: ssh command in 25.10 fails to connect with RSA key and waits To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/2130448/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
