List of the different login methods used by the server list and /server.
0 - None
1 - SASL (username + password)
2 - SASL EXTERNAL (certificate)
3 - NickServ (/MSG NickServ + Password)
4 - NickServ (/NickServ + Password)
5 - Challenge Auth (username + Password) (HMAC-SHA-256 if available, otherwise HMAC-SHA-1)
pass,sasl,external,msg,nickserv,auth can also be used for /server.