RFC 1409 Telnet Authentication Option January 1993 IAC WILL AUTHENTICATION The client side of the connection sends this command to indicate that it is willing to send and receive authentication information. IAC DO AUTHENTICATION The servers side of the connection sends this command to indicate that it is willing to send and receive authentication information. IAC WONT AUTHENTICATION The client side of the connection sends this command to indicate that it refuses to send or receive authentication information; the server side sends this command if it receives a DO AUTHENTICATION command. IAC DONT AUTHENTICATION The server side of the connection sends this command to indicate that it refuses to send or receive authentication information; the client side sends this command if it receives a WILL AUTHENTICATION command. IAC SB AUTHENTICATION SEND authentication-type-pair-list IAC SE The sender of this command (the server) requests that the remote side send authentication information for one of the authentication types listed in "authentication-type-pair-list". The "authentication-type-pair-list" is an ordered list of "authentication-type" pairs. Only the server side (DO AUTHENTICATION) is allowed to send this. IAC SB AUTHENTICATION IS authentication-type-pair IAC SE The sender of this command (the client) is sending the authentication information for authentication type "authentication-type-pair". Only the client side (WILL AUTHENTICATION) is allowed to send this. IAC SB AUTHENTICATION REPLY authentication-type-pair IAC SE The sender of this command (the server) is sending a reply to the the authentication information received in a previous IS command. Only the server side (DO AUTHENTICATION) is allowed to send this. Telnet Working Group