This is the problem I have too. It's because nmap looks at open ports on the systems. I have mostly OS X and Windows systems on the network, and all of the Windows 2000 and XP systems show that port 67 is open. Even though there is no DHCP server running on the system. Therefore, when I scan the network, more than half of the machines scanned return that they have a DHCP server, when most don't. On 10/13/04 11:23 AM, "Matthew Johnson" <matt at omega.org> wrote: > > My nmap doesn't work without an ip range (and a sudo ;) ). > And then I only get the networks. It should answer 192.168.1.1 > (linksys) and 192.168.0.1 (belkin) > > Mark:~$ sudo nmap -sT -sU -P0 -p 67-68 -oN dhcp-scan-results > 192.168.0-3.* > > Starting nmap V. 3.00 ( www.insecure.org/nmap/ ) > Interesting ports on (192.168.0.0): > Port State Service > 67/tcp filtered dhcpserver > 67/udp open dhcpserver > 68/tcp filtered dhcpclient > 68/udp open dhcpclient > > Interesting ports on (192.168.0.1): > Port State Service > 67/tcp filtered dhcpserver > 67/udp open dhcpserver > 68/tcp filtered dhcpclient > 68/udp open dhcpclient > > ... and so on with 2,3,4,5,6,7,8...19,20... > > Maybe I should let it go on? > > > > On Oct 13, 2004, at 8:51 AM, John T. Hoffoss wrote: >> nmap -sT -sU -P0 -p 67-68 -oN dhcp-scan-results >> >> On Tue, 12 Oct 2004 20:06:12 -0500, Mike Tuller >> <mtuller at ce.anoka.k12.mn.us> wrote: >>> I have a problem where there is a rouge DHCP server running on our >>> network, >>> and every once in a while, a system will grab an IP from it. Is there >>> a >>> simple way to search the network to see what servers are running as a >>> DHCP >>> server? >>> >>> Mike Tuller > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > Help beta test TCLUG's potential new home: http://plone.mn-linux.org > Got pictures for TCLUG? Beta test http://plone.mn-linux.org/gallery > tclug-list at mn-linux.org > https://mailman.real-time.com/mailman/listinfo/tclug-list _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota Help beta test TCLUG's potential new home: http://plone.mn-linux.org Got pictures for TCLUG? Beta test http://plone.mn-linux.org/gallery tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list