SCO server won't sftp to ubuntu 26

fixit_fiona

In /etc/ssh/sshd_config the following lines were added: HostbasedAcceptedKeyTypes +ssh-rsa HostKeyAlgorithms +ssh-rsa PubkeyAcceptedKeyTypes +ssh-rsa because they worked on ubuntu 24. On ubuntu 26 when on SCO the following line: sftp jsnipes@ausus1 gave: Connecting to asus1... no kex alg Connection closed The line HostKeyAlgorithms +ssh-rsa was added to /etc/ssh/ssh_config , and then on ubuntu 26 the command: sftp jsnipes@petpay worked fine!...

Originally asked by Jim Snipes on Stack Exchange (askubuntu) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

SCO is very old, and I'm honestly surprised to see one still running! The error no kex alg means there is no key exchange algorithm in common between the two sides. That's a different problem from the host key or public key settings (ssh-rsa) you've already changed. The old SSH on the SCO box only knows legacy key exchange methods, and the OpenSSH on Ubuntu 26 has most likely disabled them by default. Also, note that what you fixed (adding ssh-rsa to /etc/ssh/ssh_config on Ubuntu) only helps when Ubuntu is the client. Your title is about the opposite direction, SCO connecting to Ubuntu, so the settings that matter are the server-side ones in Ubuntu's sshd_config. Running ssh -vv from the...

Full answer by Carlos Dagorret: https://askubuntu.stackexchange.com/a/1570514 (CC BY-SA 4.0).

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