[Dnsmasq-discuss] Dhcp discover client source ip not 0.0.0.0

Sen Haerens sen at senhaerens.be
Tue May 22 11:51:08 BST 2012


Greetings,

I have a Netgear switch that is unable to acquire a DHCP lease. The
DHCP discover request is not replied according to dnsmasq & tcpdump
log. I guess the UDP src ip is a violation of the RFC.

11:26:06.106723 IP (tos 0x0, ttl 64, id 380, offset 0, flags [none],
proto UDP (17), length 281)
   192.168.0.239.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP,
Request from 74:44:01:78:e1:ed, length 253, xid 0x8274d270, Flags
[Broadcast] (0x8000)
         Client-Ethernet-Address 74:44:01:78:e1:ed
         Vendor-rfc1048 Extensions
           Magic Cookie 0x63825363
           DHCP-Message Option 53, length 1: Discover
           MSZ Option 57, length 2: 576
           Parameter-Request Option 55, length 3:
             Subnet-Mask, Default-Gateway, Domain-Name-Server

If I add a route for this IP range on the server the problem is fixed.
sudo route add -net 192.168.0.0 netmask 255.255.255.0 dev vlan20

Shouldn't the broadcast flag in the DHCP request take care of this situation?
Thank you for your assistance.



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