{"id":187,"date":"2017-10-08T22:18:32","date_gmt":"2017-10-08T13:18:32","guid":{"rendered":"https:\/\/www.ish.org\/blog\/?p=187"},"modified":"2019-11-16T10:15:46","modified_gmt":"2019-11-16T01:15:46","slug":"path-mtu-discovery%e5%95%8f%e9%a1%8c","status":"publish","type":"post","link":"https:\/\/www.ish.org\/blog\/?p=187","title":{"rendered":"openssh 7.5p1\u3060\u3068IPv6\u3067\u3064\u306a\u304c\u3089\u306a\u3044\uff08\u305d\u306e4: path mtu discovery\u554f\u984c\uff09"},"content":{"rendered":"

openssh \u3067\u81ea\u5b85\u304b\u3089\u63a5\u7d9a\u3067\u304d\u305f\u308a\u3067\u304d\u306a\u304b\u3063\u305f\u308a\u3059\u308b\u4ef6\u3067\u3059\u304c\u3001path mtu discovery\u554f\u984c\u306e\u3088\u3046\u306a\u6c17\u304c\u3057\u3066\u304d\u307e\u3057\u305f\u3002
\n conoha VPS\u304b\u3089 ping6 -s SIZE target\u3059\u308b\u3068\u3001SIZE\u304c\u5c0f\u3055\u3051\u308c\u3070\u5230\u9054\u3067\u304d\u308b\u3051\u3069\u3001\u5927\u304d\u3044\u3068\u99c4\u76ee\u3002\u305d\u3082\u305d\u3082IPv6\u3067\u306f\u9014\u4e2d\u306e\u30eb\u30fc\u30bf\u304cfragment\/reassemble\u3067\u304d\u306a\u3044\u7b48\u306a\u3093\u3060\u3051\u3069\u3001\u81ea\u5b85\u306ecarrot\u3078ping6\u3059\u308b\u3068\u3001\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3057\u3066\u9001\u3063\u305f\u306e\u306b\u5c4a\u3044\u305f\u6642\u306f\u975e\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u308c\u3066\u3044\u308b\u3002\u81ea\u5b85\u304b\u3089\u306e\u30d1\u30b1\u30c3\u30c8\u3082\u540c\u3058\u3002\u3053\u308c\u306fconoha VPS\u306e\u4e0a\u4f4d\u30eb\u30fc\u30bf\u3067\u52dd\u624b\u306b\u975e\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u305b\u3066\u3044\u308b\u3088\u3046\u306a\u6c17\u304c\u3059\u308b\u3002<\/p>\n

(1) peach(conoha VPS) -> carrot(\u81ea\u5b85)<\/span>
\n peach# ping6 -s 1406 -c 3 carrot<\/span>
\n PING6(1454=40+8+1406 bytes) 2400:8500:1302:815:163:44:174:253 –> 2400:7800::XXXX<\/span>
\n 1414 bytes from 2400:7800::XXXX, icmp_seq=0 hlim=47 time=9.491 ms<\/span>
\n 1414 bytes from 2400:7800::XXXX, icmp_seq=1 hlim=47 time=8.750 ms<\/span>
\n 1414 bytes from 2400:7800::XXXX, icmp_seq=2 hlim=47 time=5.011 ms<\/span>
\n — carrot.ish.org ping6 statistics —<\/span>
\n 3 packets transmitted, 3 packets received, 0.0% packet loss<\/span>
\n round-trip min\/avg\/max\/std-dev = 5.011\/7.751\/9.491\/1.961 ms<\/span><\/p>\n

peach# tcpdump icmp6 and host peach.ish.org and host carrot.ish.org<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on vtnet0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:23:18.350810 IP6 peach > carrot: frag (0|1232) ICMP6, echo request, seq 0, length 1232<\/span>
\n 21:23:18.350823 IP6 peach > carrot: frag (1232|182) <— (1-1)peach\u3067\u9001\u3063\u305f\u969b\u306f\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u308c\u3066\u3044\u308b<\/strong><\/span>
\n 21:23:18.360228 IP6 carrot > peach: ICMP6, echo reply, seq 0, length 1414<\/span>
\n 21:23:19.380647 IP6 peach > carrot: frag (0|1232) ICMP6, echo request, seq 1, length 1232<\/span>
\n 21:23:19.380660 IP6 peach > carrot: frag (1232|182)<\/span>
\n 21:23:19.389303 IP6 carrot > peach: ICMP6, echo reply, seq 1, length 1414<\/span>
\n 21:23:20.440677 IP6 peach > carrot: frag (0|1232) ICMP6, echo request, seq 2, length 1232<\/span>
\n 21:23:20.440690 IP6 peach > carrot: frag (1232|182)<\/span>
\n 21:23:20.445525 IP6 carrot > peach: ICMP6, echo reply, seq 2, length 1414<\/span><\/p>\n

carrot# tcpdump icmp6 and host carrot.ish.org and peach.ish.org<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on ue0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:23:18.674079 IP6 peach > carrot: ICMP6, echo request, seq 0, length 1414 <— (1-2)carrot\u3067\u53d7\u4fe1\u6642\u306f\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u308c\u3066\u3044\u306a\u3044\uff01\uff01\uff01<\/strong><\/span>
\n 21:23:18.674163 IP6 carrot > peach: ICMP6, echo reply, seq 0, length 1414<\/span>
\n 21:23:19.706515 IP6 peach > carrot: ICMP6, echo request, seq 1, length 1414<\/span>
\n 21:23:19.706599 IP6 carrot > peach: ICMP6, echo reply, seq 1, length 1414<\/span>
\n 21:23:20.762908 IP6 peach > carrot: ICMP6, echo request, seq 2, length 1414<\/span>
\n 21:23:20.762995 IP6 carrot > peach: ICMP6, echo reply, seq 2, length 1414<\/span><\/p>\n

(2) carrot -> peach<\/span>
\n carrot# ping6 -s 1400 -c 3 peach.ish.org<\/span>
\n PING6(1448=40+8+1400 bytes) 2400:7800::XXXX –> 2400:8500:1302:815:163:44:174:253<\/span>
\n 1408 bytes from 2400:8500:1302:815:163:44:174:253, icmp_seq=0 hlim=50 time=27.359 ms<\/span>
\n 1408 bytes from 2400:8500:1302:815:163:44:174:253, icmp_seq=1 hlim=50 time=5.936 ms<\/span>
\n 1408 bytes from 2400:8500:1302:815:163:44:174:253, icmp_seq=2 hlim=50 time=6.611 ms<\/span>
\n — peach.ish.org ping6 statistics —<\/span>
\n 3 packets transmitted, 3 packets received, 0.0% packet loss<\/span>
\n round-trip min\/avg\/max\/std-dev = 5.936\/13.302\/27.359\/9.944 ms<\/span><\/p>\n

carrot# tcpdump icmp6 and host carrot.ish.org and peach.ish.org<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on ue0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:30:05.096541 IP6 carrot > peach: frag (0|1232) ICMP6, echo request, seq 0, length 1232<\/span>
\n 21:30:05.096547 IP6 carrot > peach: frag (1232|176) <— (2-1)carrot\u304b\u3089\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3057\u305fecho request\u3092\u9001\u4fe1<\/strong><\/span>
\n 21:30:05.123792 IP6 peach > carrot: ICMP6, echo reply, seq 0, length 1408 <— (2-4)carrot\u3078\u5c4a\u3044\u305fecho reply \u306f\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u308c\u3066\u3044\u306a\u3044\uff01\uff01\uff01<\/strong><\/span>
\n 21:30:06.108269 IP6 carrot > peach: frag (0|1232) ICMP6, echo request, seq 1, length 1232<\/span>
\n 21:30:06.108274 IP6 carrot > peach: frag (1232|176)<\/span>
\n 21:30:06.114064 IP6 peach > carrot: ICMP6, echo reply, seq 1, length 1408<\/span>
\n 21:30:07.109867 IP6 carrot > peach: frag (0|1232) ICMP6, echo request, seq 2, length 1232<\/span>
\n 21:30:07.109873 IP6 carrot > peach: frag (1232|176)<\/span>
\n 21:30:07.116378 IP6 peach > carrot: ICMP6, echo reply, seq 2, length 1408<\/span><\/p>\n

peach# tcpdump icmp6 and host peach.ish.org and host carrot.ish.org<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on vtnet0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:30:04.788922 IP6 carrot > peach: ICMP6, echo request, seq 0, length 1408 <— (2-2)peach\u3067\u53d7\u4fe1\u3057\u305fecho request\u306f\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3055\u308c\u3066\u3044\u306a\u3044\uff01\uff01\uff01<\/strong><\/span>
\n 21:30:04.788963 IP6 peach > carrot: frag (0|1352) ICMP6, echo reply, seq 0, length 1352<\/span>
\n 21:30:04.788973 IP6 peach > carrot: frag (1352|56) <— (2-3)peach\u304b\u3089\u306eecho reply\u306f\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3057\u3066\u9001\u4fe1<\/strong><\/span>
\n 21:30:05.801132 IP6 carrot > peach: ICMP6, echo request, seq 1, length 1408<\/span>
\n 21:30:05.801180 IP6 peach > carrot: frag (0|1352) ICMP6, echo reply, seq 1, length 1352<\/span>
\n 21:30:05.801213 IP6 peach > carrot: frag (1352|56)<\/span>
\n 21:30:06.802608 IP6 carrot > peach: ICMP6, echo request, seq 2, length 1408<\/span>
\n 21:30:06.802641 IP6 peach > carrot: frag (0|1352) ICMP6, echo reply, seq 2, length 1352<\/span>
\n 21:30:06.802652 IP6 peach > carrot: frag (1352|56)<\/span><\/p>\n

(3) \u81ea\u5b85\u3067\u306f\u3061\u3083\u3093\u30683000\u30d0\u30a4\u30c8\u306eping\u304cping-tokyo.sinet.ad.jp\u3078\u5c4a\u304f<\/span>
\n carrot# ping6 -s 3000 -c 3 ping-tokyo.sinet.ad.jp<\/span>
\n PING6(3048=40+8+3000 bytes) 2400:7800::XXXX –> 2001:2f8:fd0e::3<\/span>
\n 3008 bytes from 2001:2f8:fd0e::3, icmp_seq=0 hlim=56 time=14.436 ms<\/span>
\n 3008 bytes from 2001:2f8:fd0e::3, icmp_seq=1 hlim=56 time=9.897 ms<\/span>
\n 3008 bytes from 2001:2f8:fd0e::3, icmp_seq=2 hlim=56 time=36.159 ms<\/span>
\n — ping-tokyo.sinet.ad.jp ping6 statistics —<\/span>
\n 3 packets transmitted, 3 packets received, 0.0% packet loss<\/span>
\n round-trip min\/avg\/max\/std-dev = 9.897\/20.164\/36.159\/11.461 ms<\/span><\/p>\n

carrot# tcpdump icmp6 and host carrot.ish.org and ping-tokyo.sinet.ad.jp<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on ue0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:36:51.834155 IP6 carrot > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 0, length 1232<\/span>
\n 21:36:51.834172 IP6 carrot > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:36:51.834180 IP6 carrot > 2001:2f8:fd0e::3: frag (2464|544)<\/span>
\n 21:36:51.848049 IP6 2001:2f8:fd0e::3 > carrot: frag (0|1400) ICMP6, echo reply, seq 0, length 1400<\/span>
\n 21:36:51.848286 IP6 2001:2f8:fd0e::3 > carrot: frag (1400|1400)<\/span>
\n 21:36:51.848317 IP6 2001:2f8:fd0e::3 > carrot: frag (2800|208)<\/span>
\n 21:36:52.834941 IP6 carrot > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 1, length 1232<\/span>
\n 21:36:52.834959 IP6 carrot > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:36:52.834964 IP6 carrot > 2001:2f8:fd0e::3: frag (2464|544)<\/span>
\n 21:36:52.844303 IP6 2001:2f8:fd0e::3 > carrot: frag (0|1400) ICMP6, echo reply, seq 1, length 1400<\/span>
\n 21:36:52.844516 IP6 2001:2f8:fd0e::3 > carrot: frag (1400|1400)<\/span>
\n 21:36:52.844562 IP6 2001:2f8:fd0e::3 > carrot: frag (2800|208)<\/span>
\n 21:36:53.849616 IP6 carrot > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 2, length 1232<\/span>
\n 21:36:53.849632 IP6 carrot > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:36:53.849639 IP6 carrot > 2001:2f8:fd0e::3: frag (2464|544)<\/span>
\n 21:36:53.885282 IP6 2001:2f8:fd0e::3 > carrot: frag (0|1400) ICMP6, echo reply, seq 2, length 1400<\/span>
\n 21:36:53.885476 IP6 2001:2f8:fd0e::3 > carrot: frag (1400|1400)<\/span>
\n 21:36:53.885526 IP6 2001:2f8:fd0e::3 > carrot: frag (2800|208)<\/span><\/p>\n

(4) conoha VPS\u3067\u306f\u5f53\u7136\u3060\u3081<\/span>
\n peach# ping6 -s 3000 -c 3 ping-tokyo.sinet.ad.jp<\/span>
\n PING6(3048=40+8+3000 bytes) 2400:8500:1302:815:163:44:174:253 –> 2001:2f8:fd0e::3<\/span>
\n — ping-tokyo.sinet.ad.jp ping6 statistics —<\/span>
\n 3 packets transmitted, 0 packets received, 100.0% packet loss<\/span><\/p>\n

peach# tcpdump icmp6 and host peach.ish.org and host ping-tokyo.sinet.ad.jp<\/span>
\n tcpdump: verbose output suppressed, use -v or -vv for full protocol decode<\/span>
\n listening on vtnet0, link-type EN10MB (Ethernet), capture size 262144 bytes<\/span>
\n 21:39:31.013065 IP6 peach > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 0, length 1232<\/span>
\n 21:39:31.013078 IP6 peach > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:39:31.013083 IP6 peach > 2001:2f8:fd0e::3: frag (2464|544)<\/span>
\n 21:39:32.070541 IP6 peach > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 1, length 1232<\/span>
\n 21:39:32.070555 IP6 peach > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:39:32.070560 IP6 peach > 2001:2f8:fd0e::3: frag (2464|544)<\/span>
\n 21:39:33.130554 IP6 peach > 2001:2f8:fd0e::3: frag (0|1232) ICMP6, echo request, seq 2, length 1232<\/span>
\n 21:39:33.130568 IP6 peach > 2001:2f8:fd0e::3: frag (1232|1232)<\/span>
\n 21:39:33.130573 IP6 peach > 2001:2f8:fd0e::3: frag (2464|544)<\/span><\/p>\n

\u3046\u30fc\u3093\u3001\u56f0\u3063\u305f\u306a\u3041\u3002\u4e0a\u4f4d\u30eb\u30fc\u30bf\u304c\u52dd\u624b\u306b\u975e\u30d5\u30e9\u30b0\u30e1\u30f3\u30c8\u5316\u3059\u308b\u3093\u3058\u3083\u624b\u306e\u65bd\u3057\u3088\u3046\u304c\u306a\u3044\u3002<\/p>\n

\u305d\u306e3<\/a>\u3078\u623b\u308b\u3000\u3000conoha VPS\u306epath MTU discovery blackhole\u554f\u984c\uff08\u305d\u306e1\uff09<\/a>\u3078\u7d9a\u304f<\/p>\n","protected":false},"excerpt":{"rendered":"

openssh \u3067\u81ea\u5b85\u304b\u3089\u63a5\u7d9a\u3067\u304d\u305f\u308a\u3067\u304d\u306a\u304b\u3063\u305f\u308a\u3059\u308b\u4ef6\u3067\u3059\u304c\u3001path mtu discovery\u554f\u984c\u306e\u3088\u3046\u306a\u6c17\u304c\u3057\u3066\u304d\u307e\u3057\u305f\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,4],"tags":[],"class_list":["post-187","post","type-post","status-publish","format-standard","hentry","category-ipv6","category-vps"],"_links":{"self":[{"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/187","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=187"}],"version-history":[{"count":18,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/187\/revisions"}],"predecessor-version":[{"id":1672,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/187\/revisions\/1672"}],"wp:attachment":[{"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=187"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=187"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ish.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=187"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}