没有 IAC SE 的 Te.net 子协商命令

Question

Does te.net sub negotiation command without IAC SE is valid command?

Answer 1

No, the IAC, SE sequence indicates the end of the response (and the supplied value).
See Documentation

Answer 2

Like @Robert Bradley says, a sub-option negotiation which does not end with <IAC><SE> is NOT valid.

However there is one unofficial exception, which, because it was broken like that, got replaced, but theoretically could be seen in the wild . That is the original version of the M ud C lient C ompression P rotocol (MCCP - using sub-option number 85 which uses zlib compression to reduce the amount of data bytes to be sent from a MUD (Multi-User Dungeon) Game Server to the players' Clients. That mistakenly has the Server using <IAC><SB><85><WILL><SE> at the exact point in the data where compression begins. This defect was so significant that the protocol was revised to version 2 - which is otherwise identically except that it uses the sub-option number 86 instead - so that the sequence to begin that (after both server and client have agreed) is the correctly formed: <IAC><SB><86><WILL><SE> .

MUD server and client applications are now to prefer MCCP2 over MCCP1 (and obviously not agree to do the latter if the former has already been negotiated). See also: https://smaugmuds.afkmods.com/mccp/protocol.html .