[Kea-users] DHCP4_PACKET_SEND_FAIL sendmsg() returned with an error: No route to host

[Joshua Schaeffer]

On 5/11/20 4:10 PM, Brian Hechinger wrote:
>
> It never gets to the switch in the first place. Watching tcpdump on the dhcp server I only see the requests coming in but never sending anything out.
>
That's what I figured but wanted to be sure.
>
> Traceroute doesn't work oddly enough. It just times out.
>
That can be typical in some networks as a lot of firewalls drop ICMP packets by default.
>> - How is Kea's interfaces-config map configured in kea-dhcp4.conf?
>
>     "interfaces-config": {
>         "interfaces": [ "*" ],
>         "dhcp-socket-type": "udp"
>     },
AFAIK everything looks fine. Can't give you an definitive answer as to why when Kea sends a packet the OS thinks the host has no route:

- Could be a firewall or security context issue. Check IPTables, AppArmor, SELinux, etc.
- As a test you could try changing to raw sockets (remove "dhcp-socket-type": "udp"). If that does work I'm not sure why it would as it's a relayed request.
- Force Kea to use the kernel routing table by adding  "outbound-interface": "use-routing" to the configuration (after re-adding "dhcp-socket-type": "udp" back to the config).

-- 
Thanks,
Joshua Schaeffer

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