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Hack 13 Guess the Time Zone of a User

You're almost off to bed while
other users on the channel seem to just get out of bed.
That's what happens when IRC is available all over
the world, but how can you find out if someone is likely to be
awake?

There are several ways to guess the local
time of an IRC user, but not all of them are guaranteed to be
accurate. The most obvious is to simply ask them what the time is.
But what if they aren't around to answer your
question? How do you know if they're asleep, not
there, or simply ignoring you?

First, you can try to get the user's
hostname. You
can get it using the /who or
/whois command, which reveals information about a
user [Hack #15], or maybe you have
the hostname already. Most IRC clients will offer you the option of
displaying it when a person joins or parts the channel.

In most cases, you'll see a hostname ending with a
two-character country code. Take
cc123-a.hnglo1.ov.home.nl as an example. As you may know, NL is the
abbreviation for the Netherlands. Now you can look up the current
time there. One way to do it is using the Time Zone Converter (http://www.timezoneconverter.com). You can
see it in action in Figure 3-3. If you
don't know the capital of the country, open the
Lookup Time Zone by Country link on the left.

Figure 3-3. Comparing the time in Amsterdam with GMT

There is an obvious problem when you deal
with countries that have more than one time zone. Also, with
domain extensions like .com or .net, you
can't be sure about the user's
location. Usually, they point at hosts in the United States, but
there are six U.S. time zones in the winter and seven in the summer.
Also, there is no guarantee that a .com or .net address even points
to somewhere in the United States. Fortunately,
there's still a way of finding out where these
hostnames belong. For example, you can use the Whois service to check
out where the owner of the domain name lives. If that
doesn't give any useful information, your last
chance is to fetch the Whois information for
the IP address the
user's hostname points at. To get the Whois
information, you can use the whois command
available on most Unix machines, or you can look for an
Internet Whois service, such as
http://www.register.com/whois_lookup.cgi.

The whois command can be supplied with an IP
address or hostname. For example:

% whois  t-dialin.net 

will show you something like Figure 3-4. Usually
the whois output is very long, so
you'll have to read most of it before you find what
you're looking for. This screenshot reports on a
t-dialin.net IP address. From this, you can tell that a
*.t-dialin.net address is usually located in Germany.

Figure 3-4. Whois results for a t-dialin.net IP address

By now, you should have some idea of where the user could live, but
there could still be more you need to knowfor example, some
countries have more than one time zone. There's
still one last way to find out the user's time zone.

Most IRC clients respond to the CTCP
TIME
request. They send back the local
time for the machine they're running on (assuming
the clock is set correctly). For example:

17:25:41 [ctcp(jibbler)] TIME 
17:25:42 CTCP TIME reply from Jibbler: Wed Jan 21 16:25:42 2004

As you can see, Jibbler's machine is one hour behind
the time zone I'm in. So now that you know what time
zone he could be in, I'll leave the calculations
(converting the time into a time zone) up to you.

There is one caveat to this approach. Some people log in from a
remote box. This box might be somewhere completely different from
where they live. There is only one way to be completely sure about a
person's time zone, and that is to ask her (and hope
she is telling the truth!).

Since some people don't like to receive CTCP
messages (or sometimes they make their IRC client ignore them),
it's a good idea to try the methods described
earlier first, before falling back to the CTCP TIME approach.

Wilmer van der Gaast