Telnet Server FTP warning messages 500 'AUTH GSSAPI' how to resolve??

These are the warning messages I am getting but the FTP works fine.How do I get rid of these?

220 FTP server (SunOS 5.8) ready.

500 'AUTH GSSAPI': command not understood.
500 'AUTH KERBEROS_V4': command not understood.
KERBEROS_V4 rejected as an authentication type