I have a hashed password
$6$salt$hash. I want to ssh to a linux server with this hash. How could I do that? Do I need to change cipher spec? Is that possible?
You will not be able to do that.
The password is verified by the SSH server (or better by PAM library or similar authentication backend on other platform) by taking the received password, hashing it and comparing it to the stored hashed one. There is no way to bypass this process and make the server use the hash directly for comparison.
I'm going to go out on a limb and guess that this is part of a penetration testing training programme. In which case, you can't get into the system using that hash directly, but you can pass that hash to a cracking programme, such as HashCat, which will attempt to crack the password it represents (and is much faster than online brute force).
If it's for a penetration testing training programme, the password will likely be something easily cracked, such as the "enterprise standard" password of "Password123!".
I agree with Steffen that the server will store a hash of the 'password' and verify your password by hashing it and seeing if it matches the stored value. However, I don't see why you couldn't be storing a hash of the hash resultant of the password in the server and hash the password on your side before passing it to the server.
The server would hold only: Hash(Hash(Password))
and you would be required on your side to pass: Hash(Password)
I am sure, depending on how secure your side is, this is at least a little more time consuming from a cybersecurity measure for an attacker to crack the password if taken from server side or via transmission, but cumbersome.