password troubles

[Beartooth]

	I'm having troubles getting some PCs to accept their passwords, 
either directly to sign in, or over ssh from another machine, or both. 
I've even had a situation (more than once) where A would not let me ssh 
in from B -- but I could ssh from B to C, and from C to A.

	No matter how carefully I type, watching each finger onto the 
next key ; even if I type out the password on another tab (so that I can 
inspect it), then cut & paste; I still get this :

[btth at localhost ~]$ ssh 192.168.1.123
btth at 192.168.1.123's password: 
Permission denied, please try again.
btth at 192.168.1.123's password: 
Permission denied, please try again.
btth at 192.168.1.123's password: 
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
[btth at localhost ~]$ 

	Also my old Dell PowerEdge SC1420 (long since reconfigured to be 
a PC with two hard drives, not a server with one and a backup) does not 
let me ssh in with userid, but only as root.

	I've also tried a big hammer, revising a set of known hosts. 
Sometimes that does the job; but sometimes it does only this :

[btth at localhost ~]$ nano .ssh/known_hosts
[btth at localhost ~]$ ssh 192.168.1.123
The authenticity of host '192.168.1.123 (192.168.1.123)' can't be 
established.
ECDSA key fingerprint is 36:2e:66:7e:e8:e9:96:ae:37:bd:99:da:38:5b:37:fb.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.123' (ECDSA) to the list of known 
hosts.
btth at 192.168.1.123's password: 
Permission denied, please try again.

	.... and so on, till it locks me out for trying too many times.

	Fwiw, at one point I went out and bought a nice brand spanking 
new keyboard. No change.

-- 
Beartooth Staffwright, Not Quite Clueless Power User
Remember I know little (precious little!) of where up is.