The Channel Timestamp (TS) Zero Problem
by Joseph Lo aka Jolo, last updated Aug 6, 2002
”Note”: TS0 has largely disappeared from IRC networks, with the last major network where it commonly appeared (EFNet) being updated several years ago with protocol changes which automatically updated TS0 channels to have a valid, current timestamp. The TS0 problem, is thus, a relic of thie past, and this document is largely historic.
What is a TS?
On EFnet, every channel has a timestamp or TS, which is the date and time that the channel was most recently created. Think of it as the channel birthday. The TS is very important to your channel’s security. When servers split and rejoin, they use the channel TS on both sides of the split to resolve any conflicting channel modes, including who was originally an op.
Consider the common scenario where server X splits due to some networking problems. Server X temporarily becomes a separate IRC network of its own. If nobody on your channel happened to be on server X before the split, then your channel will no longer exist there. From the point of view of server X, everybody on your channel just /quit all at once. Anybody on server X can then just /join your channel and recreate it from scratch, thus getting channel ops. (Most EFnet servers should prevent this now, but glitches are always possible.) When server X rejoins the rest of the network, whichever side with the older TS is considered the original one, and the modes are synchronized back to the way they were. In our example, the servers would fix things on the newer channel by removing ops from any new ops and undoing any other mode changes set on server X. Everything then goes on normally.
If somebody in your channel was on server X during the split, your channel stays open. When the two sides rejoin, the two TS’s are the same, so there is no problem. This is a good reason to spread your ops around on as many different servers as possible.
What is the TS 0 problem?
Many years ago, before the current TS protocol was implemented, most channels had a TS of 0 (zero), which was the default value. (Zero is the beginning of time essentially, which for IRC servers running UNIX operating systems, is defined to be 00:00:00 GMT, January 1, 1970.) If a split channel rejoins and both sides have TS of 0, both sides are just as authoritative, so in the above example, no ops would be deoped. It was thus fairly easy for somebody to take over a channel by “riding a split”. Fortunately this ended with the implementation of TS, until now.
Twice in March 2001, crackers (“hackers”) were able to link a bogus EFnet server into the network. They manipulated the TS on that server and reset it back to 0. The older TS always wins, and there is nothing older than the beginning of time itself. So when the hacked server was linked in, many channels had their TS reset from their legitimate creation dates all the way back to 0. This made them vulnerable to takeovers using the aforementioned split-riding technique.
How do I tell if my channel TS was reset to 0?
On most clients, you can check your TS with the command
which should show your channel’s current modes and when it was created. The
result may be shown on your status screen, console window, etc. For example:
/mode #irchelp *** Mode for channel #irchelp is "+tnl 25" *** #irchelp - created Sat Mar 24 03:56:59 2001
If the year is 1969 or 1970, then TS has been set back to 0 (it may be slightly different due to time zones). AFAIK older versions of mIRC does not show the TS if it is 0, so if you see your channel’s modes but no date, you have a problem. When in doubt, ask somebody not using mIRC to check for you.
How do I fix the TS 0 problem?
The only way to fix this is to “cycle” your channel: clear everybody out and recreate it from scratch. The TS will then be set to the current time and you’ll be safe. The danger of course is that whoever gets back in first is the new owner of the channel, so you need to maximize the chances that it’s one of your ops. Here’s the recommended way to do this.
- Wait until things are pretty quiet such as at night, and arrange to have a few experienced ops to help. You don’t want to do this while a lot of visitors are coming and going.
- Make sure there are no splits in progress. Use
/lusersto see if all 40 or so servers are linked. Use
/ping #channelnameto see if anybody is lagging and thus likely to split soon. If you proceed during a split, this will either not work, or you may even lose your channel!
/mode #channelname +i(invite only) to deter new vistors and auto-rejoining clients.
- Get people to leave the channel and to stay away for at least 15 minutes, by asking nicely first, then by kicking if necessary.
- When you are down to just the few experienced ops who are awake and each have one client left, wait a few minutes more. You can optionally go -i for a minute to see if anybody else is trying to sneak in.
- If you use channel maintenance bots which know how to auto-cycle the channel, get all but one bot out. Make sure the bot’s owner is around in case you need manual intervention. Then everybody should just leave and not rejoin for a minute to let the bot have time to cycle the channel.
- If you don’t use bots, just cycle the channel the old fashioned way. When you think the coast is clear, on the count of 3, all of you should leave and immediately try to rejoin the channel. By making it a race, you improve the chances that one of you is the winner instead of some outsider. It doesn’t matter which of you wins.
- The winner re-distributes ops carefully to other authorized people. Don’t forget to reset channel modes including topic, bans, etc.
If you’re not sure you can handle it, seek help with #irchelp. Be sure the person you talk to is an op (@ by their nick) before trusting them.
Will this happen again?
Who knows. We are always only as safe as our weakest link. Just be vigilant and keep an eye out on your channel TS, and reset it if necessary. If you are experienced with IRC bots or scripting, it is a good idea to have some automated means of checking all ops to make sure they belong to your authorized ops list. It takes considerable IRC experience and resources to maintain a channel, so good luck. If you don’t feel up to the task, there’s always DALnet. :-)