Hi Florian!
Ok, i just looked at the ircd-irc2 sources (more specifically, ircd-irc2_2.10.3p5.orig.tar.gz from backports.org). The Password length is defined to 20 and declared as "char passwd[PASSWDLEN+1];" (in common/struct_def.h).
Perhaps ngircd should do the same for compatibility?
I changed it to "#define CLIENT_PASS_LEN 21": 21 bytes (20 characters plus NULL byte).
Thanks!
Regards Alex