Both "net 192.168.0.1 mask 255.255.255.0" (any 192.168.0.x) and "net 192.168.0.1/24" (also any 192.168.0.x) gives an error.
**FATAL_ERROR** Wrong filter 'net 192.168.0.1 mask 255.255.255.0' (non-network bits set in "192.168.0.1 mask 255.255.255.0") on interface eth1
**FATAL_ERROR** Wrong filter 'net 192.168.0.1/24' (non-network bits set in "192.168.0.1/24") on interface eth1
According to http://www.tcpdump.org/lists/workers/2004/12/msg00056.html it's a warning/notice and not really an error.
I'm using 3.2 (it's part of Debian):
Welcome to ntop v.3.2 SourceForge .tgz
[Configured on Dec 26 2006 10:53:49, built on Dec 26 2006 10:54:23]
Copyright 1998-2005 by Luca Deri <deri@ntop.org>.
Get the freshest ntop from http://www.ntop.org/
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.