ssh error invalid digest

[Tom Goodman]

Hello Cygwin,

Can openssl 3.5.71-1 be coerced to connect to an old ssh server?

I'm not sure if this is a cygwin problem or an openssl issue, but I 
figured I would start here as the error occurs for me in cygwin.

After updating my cygwin environment to the current recommended version 
of my packages, I am seeing this error:

     tgoodman@tester04 ~
     $ ssh -o HostKeyAlgorithms=+ssh-rsa notsure
     ssh_dispatch_run_fatal: Connection to 192.168.11.3 port 22: error 
in libcrypto: invalid digest

The destination host is running Ubuntu 10.04.4 LTS. (Yes, it is 
incredibly old, but this is an interior machine and it still works, so 
no one wants to touch it.)

Several years ago I added the HostKeyAlgorithms option that was needed 
to support the old crypto. (Actually added to ~/.ssh/config, but for 
debugging I've temporarily deleted config so everything is on the 
command line.)

Claude recommended:

     tgoodman@tester04 ~
     $ ssh -o HostKeyAlgorithms=+ssh-rsa \
         -o PubkeyAcceptedKeyTypes=+ssh-rsa \
         -o 
KexAlgorithms=+diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 \
         notsure
     ssh_dispatch_run_fatal: Connection to 192.168.11.3 port 22: error 
in libcrypto: invalid digest

Since that advice came from Claude, I did not have high hopes. As 
expected, that did not fix the issue.

The unsatisfying 'fix' I have implemented is to downgrade the openssl 
and libssl3 packages from current 3.5.71-1 to the older 3.0.19-1, but 
that is not a good, long term solution.

So my question:

Can openssl 3.5.71-1 be coerced to make the connection to this old ssh 
server? If so, what options?


-- 
Tom Goodman
TomGoodman@FBE-inc.com
https://fbe-inc.com/
FBE Associates, Inc.