Public bug reported: According to RFC's a FQDN hostname may have up to 64 chars. Nevertheless ssh-keygen fails to create a key when it has exactly these 64 chars:
Hostname (edited to hide , but with same amount of chars): abcde-frontend-abcde-frontend-2-i-9b90b8d9.dyn.abcde.abcdfer.com It fails with this message: gethostname: File name too long Not being able to create a key means that openssh-server postinst will fail with this message: Setting up openssh-server (1:6.6p1-2ubuntu1) ... Creating SSH2 ED25519 key; this may take some time ...gethostname: File name too long dpkg: error processing package openssh-server (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: openssh-server E: Sub-process /usr/bin/dpkg returned an error code (1) Tested on: Ubuntu 14.04 LTS openssh-client versions tested: Installed: 1:6.6p1-2ubuntu1 Candidate: 1:6.6p1-2ubuntu2.3 Looks like s imilar bug report on RedHat bug tracker: https://bugzilla.redhat.com/show_bug.cgi?id=1097665 ** Affects: openssh (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1486654 Title: ssh-keygen fails to create keys when FQDN=64 chars To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1486654/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
