Date: Mon, 15 Feb 2016 11:26:39 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-amd64@FreeBSD.org Subject: [Bug 207208] ping has a problem with fragemented replies Message-ID: <bug-207208-6@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207208 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 di= dn't receive a response. However with tcpdump I can see the replies being receiv= ed. 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=3D0 ttl=3D245 time=3D22.851 ms --- 80.113.23.178 ping statistics --- 1 packets transmitted, 1 packets received, 0.0% packet loss round-trip min/avg/max/stddev =3D 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, len= gth 980 12:13:48.731234 IP (tos 0x0, ttl 245, id 44677, offset 0, flags [none], pro= to 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 I= CMP (1), length 1500) 192.168.93.148 > 80.113.23.178: ICMP echo request, id 54562, seq 0, len= gth 1480 12:14:45.394407 IP (tos 0x0, ttl 64, id 63325, offset 1480, flags [none], p= roto 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 on= ly seems to have problems with fragement replies. I've also tested this on Lin= ux, Mac OS X and OpenBSD and they don't seem to have this problem. I've observed this behavior on 10.2-RELEASE-p12. --=20 You are receiving this mail because: You are on the CC list for the bug.=
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