Channels can have additional constraints, which can be set by the MODE command. To understand this, recall that the first person to JOIN a channel effectively creates it and is initially ``in charge'' of the channel (``Channel Operator'' or `` chanop'') . He can subsequently add those constraints, make other people chanops at leisure.
Table: Mode commands
Public is the default mode for a channel. When someone is on a public channel, he can be seen by all other users (if his own user mode permits this). Anyone can notice users on a public channel and join such a conversation.
Private means that, although anyone can see members of such a channel, you can't tell what channel they are on unless you are already on that channel with them. They just appear as `` Prv: *'' in LIST or NAMES. Since the number of potential channels is in the billions, this is quite some security --- all you give away is the acknowledgement that you're IRC'ing.
If you are on a secret channel, someone who is not on the same channel can't even see that you are there. Your name does not show up in a LIST of active users. The only indication of your presence is that, when entering IRC , all new users are told that there are ``NNNN users on XXX servers''. If someone checks on all users and finds less than NNNN of them, he knows that other people are hiding on secret channels. But a secret channel user still cannot be found except by brute-force checking through all channels, a hopeless proposition in the face of the huge number of possible channel names. Security through obscurity finally means something.
/MODE <channel>|<nickname> [[+|-]<modechars> [<parameters>]]
allows channel operators to change channel mode, or any user to change their personal mode.
/MODE #Twilight_Zone +m *** Mode change "+m" on channel #Twilight_Zone by Nap /MODE Nap -i *** Mode change "-i" for user Nap by poly.polytechnique.fr
And this is how to give chanop status to someone on the channel:
/MODE #Twilight_Zone +o sojge *** Mode change "+o sojge" on channel #Twilight_Zone by Nap
Table: Channel modes
A + or - sign determines whether the mode should be added or deleted. Try typing `` /HELP MODE'' to get further information. Channels can be moderated (only chanops can talk), secret, private, with a limited number of users, anonymous, invite-only, topic-limited, with a list of banned users...
Table: User modes
The MODE command also allows you to modify your personal parameters, your ``user mode''. You can check your usermode with the command `` /MODE <YourNick>'' or sometimes UMODE. Note that user mode +i may be the default on some servers, in order to protect privacy of users. This should not be seen as a problem, since any user can change his personal mode whatever defaults a server may set.