Hostmask

A user's hostmask gives their nick, their username and their ip or host. It is of the form:

nick!username@host

Hostmasks are used while banning people from channels. When banning it is often wise to use wildcards in the hostmask, for example:

/mode #channel +b nick!username@host

Is easy to evade, as they only need to change their nick to be able to rejoin the channel.

/mode #channel +b *!*@host

Is more difficult to evade, as they need to change their host.

/mode #channel +b *!*@*last_part_of_host

Is even harder to evade, as it'll probably force someone to use a different ISP in order to regain access to the channel. However, the wider hostmask you set on a ban, or any other command, the more people it may uninentionally affect. It is, therefore, not recomended to ban *!*@*.