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

Sen Haerens sen at senhaerens.be
Wed May 23 08:50:02 BST 2012


Disabling source address verification for the affected interface
solves the packets being discarded by the kernel. It's enabled by
default on an Ubuntu server installation.

sysctl -w net.ipv4.conf.vlan20.rp_filter=0

Dnsmasq then, handles the lease just fine.

kubrick dnsmasq-dhcp[18951]: DHCPDISCOVER(vlan20) 192.168.168.7
74:44:01:78:e1:ed
kubrick dnsmasq-dhcp[18951]: DHCPOFFER(vlan20) 192.168.168.7 74:44:01:78:e1:ed
kubrick dnsmasq-dhcp[18951]: DHCPREQUEST(vlan20) 192.168.168.7
74:44:01:78:e1:ed
kubrick dnsmasq-dhcp[18951]: DHCPACK(vlan20) 192.168.168.7
74:44:01:78:e1:ed switch-02

IP 192.168.0.239.68 > 255.255.255.255.67: BOOTP/DHCP, Request from
74:44:01:78:e1:ed, length 259
IP 192.168.168.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 300
IP 192.168.0.239.68 > 255.255.255.255.67: BOOTP/DHCP, Request from
74:44:01:78:e1:ed, length 307
IP 192.168.168.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 300



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