Forum - Can no longer ping end point. IPv6 traffic not flowing :: SixXS

Can no longer ping end point. IPv6 traffic not flowing

Carmen Sandiego on Monday, 24 June 2013 21:02:13

Hello my setup is a debian workstation behind a debian router. Tunneling via AICCU. This has been working fine for many months. Some time on June 22 this stopped working. There have been no changes to either host. Symptoms 1. Aiccu is running and interface is up: # ifconfig sixxs sixxs Link encap:IPv6-in-IPv4 inet6 addr: fe80::ac10:6401/64 Scope:Link inet6 addr: 2604:8800:100:111::2/64 Scope:Global UP POINTOPOINT RUNNING NOARP MTU:1280 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:229 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:21720 (21.2 KiB) 2. Can ping local end point (::2), but not far end point (::1). 3. Remote IPV6 hosts cannot ping ::2. Cannot reach any IPV6 host from workstation. 4. A tcpdump on interface sixxs shows outbound, but no return traffic: 16:58:47.148458 IP6 (hlim 64, next-header TCP (6) payload length: 40) cl-274.chi-03.us.sixxs.net.36646 > schein.debian.org.http: Flags [S], cksum 0xd582 (incorrect -> 0xcd63), seq 2408097255, win 12200, options [mss 1220,sackOK,TS val 48082636 ecr 0,nop,wscale 7], length 0 16:59:03.164474 IP6 (hlim 64, next-header TCP (6) payload length: 40) cl-274.chi-03.us.sixxs.net.36646 > schein.debian.org.http: Flags [S], cksum 0xd582 (incorrect -> 0xbdbf), seq 2408097255, win 12200, options [mss 1220,sackOK,TS val 48086640 ecr 0,nop,wscale 7], length 0 What could the problem be?

Can no longer ping end point. IPv6 traffic not flowing

Carmen Sandiego on Monday, 24 June 2013 23:27:36

Further investigation reveals that the trouble might be with the router. The router is a simple eth1 inside to eth0 outside configuration. All IPV4 and NAT. Tcpdump on the router shows IPV6 traffic on eth1 but not on eth0. Forwarding is on: root@alix:/etc/shorewall# sysctl -a |grep ipv6.*forwarding error: permission denied on key 'net.ipv4.route.flush' net.ipv6.conf.all.forwarding = 1 net.ipv6.conf.all.mc_forwarding = 0 net.ipv6.conf.default.forwarding = 1 net.ipv6.conf.default.mc_forwarding = 0 net.ipv6.conf.lo.forwarding = 1 net.ipv6.conf.lo.mc_forwarding = 0 net.ipv6.conf.eth0.forwarding = 1 net.ipv6.conf.eth0.mc_forwarding = 0 net.ipv6.conf.eth1.forwarding = 1 net.ipv6.conf.eth1.mc_forwarding = 0 net.ipv6.conf.eth2.forwarding = 1 error: permission denied on key 'net.ipv6.route.flush' net.ipv6.conf.eth2.mc_forwarding = 0 IPV4 traffic like web and DNS, works fine.

Can no longer ping end point. IPv6 traffic not flowing

Jeroen Massar SixXS Staff

on Sunday, 30 June 2013 21:17:23

sixxs Link encap:IPv6-in-IPv4

Are you behind a NAT, as then likely this will not work easily/reliably.

2. Can ping local end point (::2), but not far end point (::1).

Which indicates that the tunnel is not working.

4. A tcpdump on interface sixxs shows outbound, but no return traffic:

Because that only will show the traffic that you are putting into the tunnel, not what the underlying IPv4 connectivity does with it.

What could the problem be?

Many things. Check the "Reporting Problems / Checklist" on the contact page (as indicated by the big orange/yellow box when posting) for a list of things you can check.

Please note Posting is only allowed when you are logged in.