One of the first skills new people on IRC learn, no matter if they are learning how to ignore an abusive person, add bans to a channel, or configure auto-op scripts is how to create and understand hostmasks. In order to get the most out of this guide, you may want to have an understanding of How to identify someone on IRC.

What is Hostmask?

A hostmask is how scripts, bans, ignores, and some bots, determine someone's identity on IRC. Everyone who logs onto IRC has a nickname, a UserID (or `ident'), and a host. If you are on a Unix system, your UserID is likely your login name. On a Windows machine, you likely are able to set your UserID yourself.


Your nickname is the main identifier used on IRC, but you can change nicks easily during your session, thus, it is a poor identifier. Likewise, because Windows users often set their own UserID, it is only a semi-reliable identifier. Your host is the Internet IP address or hostname you are connecting from. Most people can only change it by logging in with a different ISP. It is a strong identifier, although parts of it may change every time you log in, and a group of people share the same domain name.

The nickname, UserID, and host are often represented as:


You are probably familiar with the format `userid@host' for e-mail addresses. Although usually a host on IRC is not exactly the same as a person's e-mail address, the concept is similar. To get a mask, simply take the nickname!UserID@Host string, and replace the parts which you expect may change with wild cards. Two wild cards, “*” (asterisk) and “?” (question mark) are understood. The “*” means “match any number of characters”, and the “?” means “match exactly one character.”

Masks in practice

For example, my user@host string is Krobar!, but if I added myself to the userlist that way and I didn't use the nickname Krobar one day, I wouldn't be recognized. On the flip side, if I added myself as *!*@*, then everyone would match. A typical mask is *!*UserID@*.Host This way any nickname used, from any machine in the domain is matched. The * in front of a UserID is usually a good idea, because some servers will add a ~ in front if identd (a nameserver of sorts) isn't working or is too slow. I typically add myself as *!*

IP Addresses

Sometimes when DNS is slow or broken, someone might show up with only their IP address as a host. In this case, it's the end that changes, so a mask like this might be what you want: *!*UserID@Host.* My mask, in this case would be: *!*krobar@128.193.14?.* Note the use of “?” in the IP portion. Sometimes my IP is 128.193.141.* and sometimes its 128.193.142.*. Adding a ? ensures I will be recognized, but without too much chance of accidentally recognizing someone else. EXAMPLES: To match everyone with a .br country ending:


To match everyone with nick “warez”:


To match your friend John (John!


When John complains that he's not recognized when he dials in from Florida:


To match John when his IP shows up instead:


To match people with the tell-tale “typehere” userid: