Troubleshooting: DHCP Debugging with NMAP

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Revision as of 12:49, 12 November 2019 by David (talk | contribs) (Created page with "<syntaxhighlight> GE-Test 12:44:27 [root@p2postvpo1 ~]# vi /usr/share/nmap/scripts/broadcast-dhcp-discover.nse GE-Test 12:45:16 [root@p2postvpo1 ~]# nmap --script broadcast-dhcp-discover...")
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GE-Test 12:44:27 [root@p2postvpo1 ~]# vi /usr/share/nmap/scripts/broadcast-dhcp-discover.nse
GE-Test 12:45:16 [root@p2postvpo1 ~]# nmap --script broadcast-dhcp-discover -e eth0 

Starting Nmap 6.40 ( http://nmap.org ) at 2019-11-12 12:45 UTC
Pre-scan script results:
| broadcast-dhcp-discover: 
|   IP Offered: 10.6.44.254
|   DHCP Message Type: DHCPOFFER
|   Server Identifier: 10.6.44.101
|   IP Address Lease Time: 0 days, 0:02:00
|   Renewal Time Value: 0 days, 0:01:00
|   Rebinding Time Value: 0 days, 0:01:45
|   Subnet Mask: 255.255.252.0
|   Broadcast Address: 10.6.47.255
|   Domain Name: openstacklocal
|   Hostname: host-10-6-44-254
|   Router: 10.6.44.2
|   Domain Name Server: 10.6.44.254
|_  Interface MTU: 9000
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 0.13 seconds
GE-Test 12:45:19 [root@p2postvpo1 ~]#

Use the nmap script above - change the MAC address to the local interface (if DHCP service is Mac restricted) and use nmap to test the DHCP offers...