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Author Topic: How to get default route set up properly.  (Read 7707 times)

maestro

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How to get default route set up properly.
« on: November 29, 2010, 12:16:12 PM »

Hi, I have just started trying to get a tunnel working, and the tunnel appears to come up OK, however I can't seem to get packets to route through the tunnel.

When I try to ping "ipv6.google.com" or "2404:6800:8004::68" (google's ipv6 address) then it doesn't attempt to send any packets out the tunnel.
# ping6 2404:6800:8004::68
connect: Network is unreachable
ping6 ipv6.google.com
connect: Network is unreachable


The script that I use to start the tunnel is as follows...
ip tunnel add he-ipv6 mode sit remote 72.52.104.74 local 192.168.1.253 ttl 255
ip link set he-ipv6 up
ip addr add 2001:470:1f04:158f::2/64 dev he-ipv6
ip route add ::/0 dev he-ipv6
ip -f inet6 addr

my routing table looks like this (I assume that the fe80 lines are the equivalent of localhost?)...
# ip -f inet6 route
2001:470:1f04:158f::/64 via :: dev he-ipv6  metric 256  expires 21334117sec mtu 1480 advmss 1420 hoplimit 4294967295
fe80::/64 dev eth0  metric 256  expires 20967010sec mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev eth0.10  metric 256  expires 20967010sec mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev eth0.100  metric 256  expires 20967010sec mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev eth0.101  metric 256  expires 20967010sec mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev eth0.20  metric 256  expires 20967010sec mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 via :: dev he-ipv6  metric 256  expires 21334102sec mtu 1480 advmss 1420 hoplimit 4294967295
default dev he-ipv6  metric 1024  expires 21334133sec mtu 1480 advmss 1420 hoplimit 4294967295

I can ping my own address (and tcpdump shows no packets on the tunnel, as expected)
# ping6  2001:470:1f04:158f::2
PING 2001:470:1f04:158f::2(2001:470:1f04:158f::2) 56 data bytes
64 bytes from 2001:470:1f04:158f::2: icmp_seq=0 ttl=64 time=0.114 ms

When I ping an address within my /64 range, it sends it out the tunnel, and I can see it going out with tcpdump, and an ICMP redirect coming back through the tunnel. I presume that this is because I haven't yet configured any local ipv6 and that this is expected behaviour given the touring table above.
# ping6  2001:470:1f04:158f::8
PING 2001:470:1f04:158f::8(2001:470:1f04:158f::8) 56 data bytes
--- 2001:470:1f04:158f::8 ping statistics ---
73 packets transmitted, 0 received, 100% packet loss, time 71991ms

I am using CentOS 5.2
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maestro

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Re: How to get default route set up properly.
« Reply #1 on: November 30, 2010, 03:30:21 AM »

OK, I managed to fix it by adding the following line to my script...

ip route add 2000::/3 dev he-ipv6


I believe that this is a bit of a hack, but will look into it in more detail once I have a bit more experience with IPv6
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cholzhauer

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Re: How to get default route set up properly.
« Reply #2 on: November 30, 2010, 05:31:14 AM »

I've seen that line included in instructions for certain variations of linux, but I can't remember off the top of my head which ones it was.

If it helps, I'm sure you're not the only one with that route in your config.
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kriteknetworks

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Re: How to get default route set up properly.
« Reply #3 on: November 30, 2010, 09:30:49 AM »

manual defaultroute broken in 2.6.20.[5..13], 2.6.21.[0..4], RHEL/CentOS 5.[012], use 2000::/3

Its a known problem.
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maestro

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Re: How to get default route set up properly.
« Reply #4 on: November 30, 2010, 12:03:23 PM »

OK, I am using 2.6.18 (the default for CentOS 5.2)

I read somewhere that it was broken for 2.4 kernels so I thought I would try it even though mine was 2.6.

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lukec

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Re: How to get default route set up properly.
« Reply #5 on: December 03, 2010, 06:46:33 AM »

I'd suggest :-

Code: [Select]
ip route add ::/0 dev he-ipv6
for the default route
rgds
lukec
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broquea

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Re: How to get default route set up properly.
« Reply #6 on: December 03, 2010, 08:25:44 AM »

for 2.6.18, try: ip route add 2000::/3 dev he-ipv6

Manual default route is pretty broken in that kernel for RHEL based distros.
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