SSH protocol v.1 is no longer supported

Question

Trying to scp files to my server like I've done every day for years... got this weird error today:

client$ scp filename.file server:/path/to/somewhere/
SSH protocol v.1 is no longer supported
client$ echo $?
255

The file does not show up on my server like it would normally after running this command.

This error only appears on scp commands. Using ssh to get into my server works fine.

Has anyone seen this before? How do I go about debugging this? Here's some version info:

client$ ssh -V
OpenSSH_8.2p1 Ubuntu-4ubuntu0.1, OpenSSL 1.1.1f  31 Mar 2020

client$ apt show openssl
Package: openssl
Version: 1.1.1f-1ubuntu2

server$ apt show openssh-server
Package: openssh-server
Version: 1:7.2p2-4ubuntu2.10

server$ sshd -V
unknown option -- V
OpenSSH_7.2p2 Ubuntu-4ubuntu2.10, OpenSSL 1.0.2g  1 Mar 2016

(note that I've added hostnames "client" and "server" for clarity)

In my sshd_config, it shows Protocol 2

server$ cat /etc/ssh/sshd_config | grep Protocol
Protocol 2

I'm running Ubuntu 16.04 on my server, which should have maintenance updates through today.

Let me know if I should run any other operations. Server is local network only, but I still want to make sure it's hardened.

Answer 1

Ugh, it was a typo... Keeping the post up for others who bang their head against the wall on this as I couldn't find any info on this error message from googling.

It's not in the ssh command (removed various parts for privacy), but I was supplying a port:

scp -p3122 file server:/path/

But it really should be:

scp -P3122 file server:/path/

(Use a capital 'P')

Answer 2

I have the same message with the command 'SSH'. I fix the problem: that work ONLY if you use 3 elements: ssh server -l user -p port .. And the party continue..