A sequence of authentication methods. Each octet represents
a method to authenticate the user accessing the snmp-server.
Each octet has the following enumeration value:
enable(1) - authenticate by command line interface
enable password
radius(2) - authenticate by requesting radius server
local(3) - authenticate by local user account table
line(4) - authenticate by telnet password
tacplus(5) - authenticate by requesting tacplus server
none(6) - do not authenticate
tacacs(7) - authenticate by requesting tacacs server
Setting a zero length octet string invalidates all
previous authentication methods.