I'm fairly sure that the real cause of the metaserver DOS is not some
random attacker but the crossfire server itself: you just need to set up
a (new) crossfire server and change the "metaserver_notification off"
config option to "on" to make your server flood the metaserver.
The patch
cvs diff -r 1.9 -r 1.10 lib/settings
changed the default value for the "fastclock" config option from 0 to 1.
That probably means that many new servers will run in fastclock mode.
Furthermore, socket/loop.c contains a logic error if fastclock is
enabled:
(excerpt from socket/loop.c; I stripped code not related to the problem)
| /** Waits for new connection */
| static void block_until_new_connection() {
| do {
| /* Every minutes is a bit often for updates - especially if
| * nothing is going on. This slows it down to every 6 minutes.
| */
| cycles++;
| if (cycles == 7) {
| metaserver_update();
| cycles=1;
| }
| if (settings.fastclock > 0) {
| Timeout.tv_sec=0;
| Timeout.tv_usec=50;
| } else {
| Timeout.tv_sec=60;
| Timeout.tv_usec=0;
| }
| }
| while (select([...], &Timeout)==0);
[...]
This function is called whenever a server has no active connections.
Basically, with fastclock=0, the metaserver update will be sent once per
6 minutes but with fastclock=1 it will be sent once per 6*50 usec (which
could be more than 3000 packets per second on a fast machine).
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