[Dnsmasq-discuss] bad udp cksum

[e9hack]

Hi,

I capture the DNS traffic of dnsmasq with tcpdump:

root at WLAN-DSL6a:~# /tmp/tcpdump -i br-lan -vv -s 0 -l -n port 53
tcpdump: listening on br-lan, link-type EN10MB (Ethernet), capture size 65535 bytes
09:30:32.218876 IP (tos 0x0, ttl 128, id 16449, offset 0, flags [none], proto UDP (17),
length 72)
    192.168.100.2.55225 > 192.168.100.1.53: [udp sum ok] 1+ PTR?
1.100.168.192.in-addr.arpa. (44)
09:30:32.911458 IP (tos 0x0, ttl 64, id 55975, offset 0, flags [DF], proto UDP (17),
length 100)
    192.168.100.1.53 > 192.168.100.2.55225: [bad udp cksum 0x49b6 -> 0x69fe!] 1* q: PTR?
1.100.168.192.in-addr.arpa. 1/0/0 1.100.168.192.in-addr.arpa. PTR WLAN-DSL6a.lan. (72)

All udp packets from dnsmasq have a wrong udp check sum. Is this a problem of dnsmasq or
the linux itself? Dnsmasq runs on OpenWRT. The version is 2.69test8-5-ge3ec15a.

Kind regards,
Hartmut