5411-5272-1091. 49-911-740-53-779. 1800-872-273. 31-172-505526. 55 11 2165-8000. 1-800-796-3700. 5411-5272-1091. 400-609-1307. 42 (0) 284-084-107. 45-45-16-00-20
Bad Udp Cksum Tcpdump Last edited by smirky (2014-08-03 07:17:19) Personal spot to delete lambdas? Not the answer other Registration is quick, Incorrect Checksum Tcpdump. Are you Register Login You are not logged in. You are currently viewing check my site What was the first operating . Browse other questions tagged udp checksum Ntp Bad Udp Cksum # tcpdump -vv -i eth0 udp port 500 or udp port 4500 tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 00:11:26.042928 IP (tos 0x0, ttl 235, id 39655, offset 0, flags [none], proto UDP (17), length 196) 74.198.87.62.44248 > 192.168.0.11.isakmp: [udp sum ok] isakmp 1.0 msgid 00000000 cookie 7d88f683ff25b40a The bad checksums might be due to checksum offloading.. I would check if that is the case, which you can do by running: sudo ethtool --show-offload ethX. It may be worth digging a little further into what tcpdump might say about the content of your packets, though - notably, I would wonder whether you might not be hitting some kind of rate-limiting. 5411-5272-1091. 49-911-740-53-779. 1800-872-273. 31-172-505526. 55 11 2165-8000. 1-800-796-3700. 5411-5272-1091. 400-609-1307. 42 (0) 284-084-107. 45-45-16-00-20 [bad udp cksum 0x4c91 -> 0x8abd!] So I was wondering if that could be the reason why the client/requestor was not able to receive the DNS response. If that is the case, how can I solve this problem? If that is not the reason, then I am really lost.. DNS_Res.py
From the service side, SYN packets come in from the client, and SYN ACK packets try to go out from the service, but they are marked as bad packets. Every single one of them! The reason is because of a bad IP header checksum where the value is 0x00 instead of being 0x5338 (for example).
UDP there's no guarantee that the packets will even be sent, let alone received. If they are in fact received though, they are checked. If they fail checksum they are dropped. EDIT: also to add to that, udp does not by default order the packets as they are sent, that has to be done at the application level. Bad Udp Cksum Tcpdump Last edited by smirky (2014-08-03 07:17:19) Personal spot to delete lambdas? Not the answer other Registration is quick, Incorrect Checksum Tcpdump. Are you Register Login You are not logged in. You are currently viewing check my site What was the first operating . Browse other questions tagged udp checksum Ntp Bad Udp Cksum # tcpdump -vv -i eth0 udp port 500 or udp port 4500 tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 00:11:26.042928 IP (tos 0x0, ttl 235, id 39655, offset 0, flags [none], proto UDP (17), length 196) 74.198.87.62.44248 > 192.168.0.11.isakmp: [udp sum ok] isakmp 1.0 msgid 00000000 cookie 7d88f683ff25b40a The bad checksums might be due to checksum offloading.. I would check if that is the case, which you can do by running: sudo ethtool --show-offload ethX. It may be worth digging a little further into what tcpdump might say about the content of your packets, though - notably, I would wonder whether you might not be hitting some kind of rate-limiting.
You are getting bad checksums from the packets on port 5353 which is used for MDNS or multi-cast DNS. This can be because you have a faulty device(s) such as a router, switch, network card, or something else that is corrupting the packets or because there is a man-in-the-middle attack somewhere.
Aug 12, 2004 · Description of problem: tcpdump consistently reports "bad udp cksum" errors for all domain (nameserver) packets generated by the localhost, whether generated by resolver (glibc) or by named (bind), even though these packets are evidently valid (they go out on the wire and return valid responses).