TomatoUSB

UPD: (see old below)
Can't make duckdns work. cat /tmp/var/lib/mdu/ddnsx1.msg gives:
Update successful

however, my admin panel says the last update was a month ago.

just spent another half an hour trying to find out where it stores config and log files… any ideas?

just answered it myself:
root@tomatousb:/opt# find / | grep ddns
/sbin/ddns-update
/tmp/var/lock/ddns.lock
/tmp/var/lib/mdu/ddnsx1.conf
/tmp/var/lib/mdu/ddnsx1.msg
/tmp/var/lib/mdu/ddnsx1.cache
/tmp/var/lib/mdu/ddnsx0.conf
/tmp/var/lib/mdu/ddnsx0.msg
/tmp/var/lib/mdu/ddnsx0.cache
/www/basic-ddns.asp