Basic Auth
S1#enable S1#configure t Enter configuration commands, one per line. End with CNTL/Z. S1(config)#line console 0 S1(config-line)#password cisco S1(config-line)#login S1(config-line)#end S1#exit
LAB

SSH Setup
R1#enable R1#config t Enter configuration commands, one per line. End with CNTL/Z. R1(config)#ip domain-name got.com R1(config)#crypto key generate rsa general-keys modulus 1024 The name for the keys will be: R1.got.com

% The key modulus size is 1024 bits
% Generating 1024 bit RSA keys, keys will be non-exportable…[OK]

*Mar 1 00:07:14.915: %SSH-5-ENABLED: SSH 1.99 has been enabled
R1(config)#line vty 0 4
R1(config-line)#transport input ssh

I had this issue when I was SSHing from a Linux node where I had to use ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 user@router-ip. I need to grok the issue.