I started with a fresh ~/.ssh/known_hosts and first tried connecting to a a remote machine using SFTP in Dolphin. The record this wrote to ~/.ssh/known_hosts begins with "[hostname]:port ssh-rsa". Apparently, SFTP in Kubuntu 15.04 does not handle ECDSA keys, which are what SSH creates by default. However, SSH does seem to handle RSA keys, I was able to connect to the remote machine with the key.
The workaround is to first connect using SFTP to any remote machine if you need to connect to it using both SSH and SFTP. Incidentally, I did build and install libssh from the latest source (v. 0.7.1), which made no difference. The libssh.org site (https://www.libssh.org/documentation/) says, "KDE uses libssh to implement the sftp module to allow secure file transfers between different computers." That doesn't appear to be true at least in Kubuntu 15.04. More on this bug here: https://bugs.kde.org/show_bug.cgi?id=274170 ** Bug watch added: KDE Bug Tracking System #274170 https://bugs.kde.org/show_bug.cgi?id=274170 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1450085 Title: kio_sftp can't connect to hosts after OpenSSH 6 has cached their ECDSA key To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/kde-runtime/+bug/1450085/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs