Date: Mon, 15 Feb 2016 11:26:39 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 207208] ping has a problem with fragemented replies Message-ID: <bug-207208-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207208 Bug ID: 207208 Summary: ping has a problem with fragemented replies Product: Base System Version: 10.2-RELEASE Hardware: amd64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: bin Assignee: freebsd-bugs@FreeBSD.org Reporter: jasper@siepkes.nl CC: freebsd-amd64@FreeBSD.org CC: freebsd-amd64@FreeBSD.org When using ping with a packet size larger then the interfaces MTU (in my example 1500) which leads to a fragemented reply ping will always say it didn't receive a response. However with tcpdump I can see the replies being received. Single ping request with a total packet size of a 1000 bytes (within MTU of interface): ---8<------------------ $ ping -c 1 -s 972 80.113.23.178 PING 80.113.23.178 (80.113.23.178): 972 data bytes 980 bytes from 80.113.23.178: icmp_seq=0 ttl=245 time=22.851 ms --- 80.113.23.178 ping statistics --- 1 packets transmitted, 1 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 22.851/22.851/22.851/0.000 ms ---8<------------------ Resulting tcpdump output: ---8<------------------ # tcpdump -nvvvs 9000 -i igb0 icmp 12:13:48.708408 IP (tos 0x0, ttl 64, id 63061, offset 0, flags [none], proto ICMP (1), length 1000) 192.168.93.148 > 80.113.23.178: ICMP echo request, id 50210, seq 0, length 980 12:13:48.731234 IP (tos 0x0, ttl 245, id 44677, offset 0, flags [none], proto ICMP (1), length 1000) 80.113.23.178 > 192.168.93.148: ICMP echo reply, id 50210, seq 0, length 980 ---8<------------------ Single ping request with a requested payload size of 2500 bytes (which will result in a packet larger then MTU of interface): ---8<------------------ ping -c 1 -s 2500 80.113.23.178 PING 80.113.23.178 (80.113.23.178): 2500 data bytes --- 80.113.23.178 ping statistics --- 1 packets transmitted, 0 packets received, 100.0% packet loss ---8<------------------ Resulting tcpdump output: ---8<------------------ # tcpdump -nvvvs 9000 -i igb0 icmp 12:14:45.394397 IP (tos 0x0, ttl 64, id 63325, offset 0, flags [+], proto ICMP (1), length 1500) 192.168.93.148 > 80.113.23.178: ICMP echo request, id 54562, seq 0, length 1480 12:14:45.394407 IP (tos 0x0, ttl 64, id 63325, offset 1480, flags [none], proto ICMP (1), length 1048) 192.168.93.148 > 80.113.23.178: ip-proto-1 12:14:45.418429 IP (tos 0x0, ttl 245, id 23347, offset 0, flags [+], proto ICMP (1), length 1500) 80.113.23.178 > 192.168.93.148: ICMP echo reply, id 54562, seq 0, length 1480 12:14:45.418436 IP (tos 0x0, ttl 245, id 23347, offset 1480, flags [none], proto ICMP (1), length 1048) 80.113.23.178 > 192.168.93.148: ip-proto-1 ---8<------------------ Beware that some hosts will just truncate the echo reply even if you send a large packet. 'www.nu.nl' does this for example (probably to prevent getting dos'ed). The echo reply is then not fragmented and ping works fine. ping only seems to have problems with fragement replies. I've also tested this on Linux, Mac OS X and OpenBSD and they don't seem to have this problem. I've observed this behavior on 10.2-RELEASE-p12. -- You are receiving this mail because: You are the assignee for the bug.help
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