Destination unreablable one way, works the other.

[BrianVanderburgII]

I've got a tunnel set up on my home computer and another set up on my VPS. I just created the tunnel used for my VPS a short while ago.  I can ping ipv6.google.com just fine from both, and can even do other HTTP traffic just fine.  When I ping home from the VPS, it works fine and trace route works fine.  When I ping the VPS from home, I get messages about destination unreachable, but the packets still succeed, like 3 sent, 3 received, 3 errors, 0 lost.  Also, when I trace route from home to VPS, sometimes I errors, other times I get the route correctly.  When I check the address in a browser, sometimes I get an error that it can't connect, and other times I get success showing the default HTML page.  I've tested this with both the client address numbers (2001:470:4:...) and the routed numbers (2001:470:5:...) but get the same results.  What could be causing this problem and what can I do to fix it?

Home

Code Select Expand


#auto tun6to4
iface tun6to4 inet6 v4tunnel
    endpoint 209.51.161.58
    address 2001:470:4:82e::2
    gateway 2001:470:4:82e::1
    netmask 64
    ttl 255
    mtu 1480


VPS

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auto v6to4
iface v6to4 inet6 static
    pre-up setsid /root/tb_userspace v6to4 209.51.161.58 192.3.16.114 sit > /dev/null &
    pre-up sleep 1
    pre-up ip -6 route del default
    post-down killall tb_userspace
    address 2001:470:5:2a::2
    gateway 2001:470:5:2a::1
    netmask 64
    ttl 255
    mtu 1480


Ping test

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64 bytes from 2001:470:5:2a::2: icmp_seq=1 ttl=63 time=53.4 ms
From 2001:470:4:82e::1 icmp_seq=1 Destination unreachable: Address unreachable
From 2001:470:4:82e::1 icmp_seq=2 Destination unreachable: Address unreachable
64 bytes from 2001:470:5:2a::2: icmp_seq=2 ttl=63 time=54.1 ms
64 bytes from 2001:470:5:2a::2: icmp_seq=3 ttl=63 time=55.0 ms
From 2001:470:4:82e::1 icmp_seq=3 Destination unreachable: Address unreachable
64 bytes from 2001:470:5:2a::2: icmp_seq=4 ttl=63 time=52.3 ms
From 2001:470:4:82e::1 icmp_seq=4 Destination unreachable: Address unreachable
^C
--- 2001:470:5:2a::2 ping statistics ---
4 packets transmitted, 4 received, +4 errors, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 52.381/53.750/55.002/0.996 ms


Traceroute test

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traceroute to 2001:470:5:2a::2 (2001:470:5:2a::2), 30 hops max, 80 byte packets
1  2001:470:4:82e::1 (2001:470:4:82e::1)  42.202 ms  43.432 ms  44.905 ms
2  2001:470:4:82e::1 (2001:470:4:82e::1)  61.737 ms !H  61.806 ms !H  63.441 ms !H
...
traceroute to 2001:470:5:2a::2 (2001:470:5:2a::2), 30 hops max, 80 byte packets
1  2001:470:4:82e::1 (2001:470:4:82e::1)  40.834 ms * *
2  2001:470:5:2a::2 (2001:470:5:2a::2)  55.555 ms  55.544 ms  55.621 ms
[code]

[BrianVanderburgII]

I repeated the tests and still got the same problems.  I deleted the VPS tunnel and created a new tunnel using 209.51.161.14 instead.  After I updated the /etc/network/interfaces.tail on the VPS and rebooted, I was able to successfully ping from my PC to the VPS and back with no destination unreachable issues and can connect to the server via IPv6 as well.  Could the problem be two locations using the same tunnel trying to connect to each other (originally both used 209.51.161.58)?

[cholzhauer]

Two locations shouldn't be using the same tunnel...you should have a separate tunnel for each location.

[BrianVanderburgII]

The problem seems to be back.

My computer

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PING 2001:470:1f06:65::2(2001:470:1f06:65::2) 56 data bytes
64 bytes from 2001:470:1f06:65::2: icmp_seq=1 ttl=58 time=94.6 ms
From 2001:470:0:5d::2 icmp_seq=1 Destination unreachable: Address unreachable
64 bytes from 2001:470:1f06:65::2: icmp_seq=2 ttl=58 time=110 ms
From 2001:470:0:5d::2 icmp_seq=2 Destination unreachable: Address unreachable
From 2001:470:0:5d::2 icmp_seq=3 Destination unreachable: Address unreachable
64 bytes from 2001:470:1f06:65::2: icmp_seq=3 ttl=58 time=96.7 ms
64 bytes from 2001:470:1f06:65::2: icmp_seq=4 ttl=58 time=91.8 ms
From 2001:470:0:5d::2 icmp_seq=4 Destination unreachable: Address unreachable
64 bytes from 2001:470:1f06:65::2: icmp_seq=5 ttl=58 time=88.6 ms
From 2001:470:0:5d::2 icmp_seq=5 Destination unreachable: Address unreachable
^C
--- 2001:470:1f06:65::2 ping statistics ---
5 packets transmitted, 5 received, +5 errors, 0% packet loss, time 4005ms
rtt min/avg/max/mdev = 88.644/96.558/110.836/7.646 ms


Code Select Expand


traceroute to 2001:470:1f06:65::2 (2001:470:1f06:65::2), 30 hops max, 80 byte packets
1  2001:470:4:82e::1 (2001:470:4:82e::1)  39.139 ms  40.581 ms  42.257 ms
2  ge2-3.core1.mia1.he.net (2001:470:0:8c::1)  45.196 ms  45.569 ms  45.644 ms
3  10ge1-1.core1.atl1.he.net (2001:470:0:a6::2)  61.218 ms  63.554 ms  63.610 ms
4  10ge16-5.core1.ash1.he.net (2001:470:0:1b5::1)  72.487 ms  72.581 ms  74.551 ms
5  100ge7-1.core1.nyc4.he.net (2001:470:0:299::2)  83.283 ms  83.138 ms  83.211 ms
6  tserv1.nyc4.he.net (2001:470:0:5d::2)  81.468 ms  72.926 ms  75.009 ms
7  tserv1.nyc4.he.net (2001:470:0:5d::2)  94.714 ms !H  97.254 ms !H BrianVanderburgII-2-pt.tunnel.tserv4.nyc4.ipv6.he.net (2001:470:1f06:65::2)  98.381 ms


Code Select Expand


auto tun6to4
iface tun6to4 inet6 v4tunnel
    endpoint 209.51.161.58
    address 2001:470:4:82e::2
    gateway 2001:470:4:82e::1
    netmask 64
    ttl 255
    mtu 1480


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2001:470:4:82e::1 dev tun6to4  metric 1024
2001:470:4:82e::/64 dev tun6to4  proto kernel  metric 256
2001:470:5:82e:1::/80 dev vmtun  proto kernel  metric 256
fe80::/64 dev eth0  proto kernel  metric 256
fe80::/64 dev vmhost  proto kernel  metric 256
fe80::/64 dev vmnat  proto kernel  metric 256
fe80::/64 dev vmtun  proto kernel  metric 256
default via 2001:470:4:82e::1 dev tun6to4  metric 1024


VPS

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PING 2001:470:4:82e::2(2001:470:4:82e::2) 56 data bytes
64 bytes from 2001:470:4:82e::2: icmp_seq=1 ttl=58 time=88.5 ms
64 bytes from 2001:470:4:82e::2: icmp_seq=2 ttl=58 time=85.9 ms
64 bytes from 2001:470:4:82e::2: icmp_seq=3 ttl=58 time=85.8 ms
64 bytes from 2001:470:4:82e::2: icmp_seq=4 ttl=58 time=86.3 ms
^C
--- 2001:470:4:82e::2 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 85.820/86.680/88.539/1.112 ms


Code Select Expand


traceroute to 2001:470:4:82e::2 (2001:470:4:82e::2), 30 hops max, 80 byte packets
1  BrianVanderburgII-2.tunnel.tserv4.nyc4.ipv6.he.net (2001:470:1f06:65::1)  21.372 ms  33.296 ms  34.033 ms
2  ge3-8.core1.nyc4.he.net (2001:470:0:5d::1)  36.979 ms  36.917 ms  31.139 ms
3  100ge5-1.core1.ash1.he.net (2001:470:0:299::1)  52.469 ms  52.413 ms  52.374 ms
4  10ge1-2.core1.atl1.he.net (2001:470:0:1b5::2)  52.261 ms  52.234 ms  52.191 ms
5  10ge4-1.core1.mia1.he.net (2001:470:0:a6::1)  68.646 ms  68.623 ms  62.437 ms
6  tserv1.mia1.he.net (2001:470:0:8c::2)  62.380 ms  55.068 ms  61.097 ms
7  2001:470:4:82e::2 (2001:470:4:82e::2)  96.675 ms  101.245 ms  101.194 ms
[code]
auto v6to4
iface v6to4 inet6 static
pre-up setsid /root/tb_userspace v6to4 209.51.161.14 192.3.16.114 sit > /dev/null &
pre-up sleep 1
pre-up ip -6 route del default
post-down killall tb_userspace
address 2001:470:1f06:65::2
gateway 2001:470:1f06:65::1
netmask 64
ttl 255
mtu 1480


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2001:470:1f06:65::/64 dev v6to4  proto kernel  metric 256  mtu 1480 advmss 1420 hoplimit 4294967295
fe80::/64 dev v6to4  proto kernel  metric 256  mtu 1480 advmss 1420 hoplimit 4294967295
default via 2001:470:1f06:65::1 dev v6to4  metric 1  mtu 1480 advmss 1420 hoplimit 4294967295


My computer is using the tunnel 209.51.161.58
The VPS is using the tunnel 209.51.161.14
So I'm using different tunnel endpoints for each location. It doesn't seem to be causing connection problems as I can still connect to the web server unlike before, but I am curious as to why I am getting destination unreachable replies from 2001:470:0:5d::2 when pinging from my computer to the VPS even though the ping still succeeds, but no issues at all when pinging from the VPS to my computer.