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Re: IPv6 router is not forwarding packets




Hi Ulf,

Am Sonntag, 6. Januar 2019, 19:32:46 CET schrieb Ulf Volmer:
> On 06.01.19 18:36, Rainer Dorsch wrote:
> > Endpoint:
> > ---------
> > rd@mohot:~$ ip addr show dev eth0
> > 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> > UP group default qlen 1000
> > 
> >    link/ether d0:63:b4:00:4d:d1 brd ff:ff:ff:ff:ff:ff
> >    inet 192.168.7.31/24 brd 192.168.7.255 scope global eth0
> >    
> >       valid_lft forever preferred_lft forever
> >    
> >    inet6 2a02:8070:898f:e400:d263:b4ff:fe00:4dd1/64 scope global dynamic
> > 
> > mngtmpaddr
> > 
> >       valid_lft 7030sec preferred_lft 3430sec
> >    
> >    inet6 2a02:8070:898f:e4f8:d263:b4ff:fe00:4dd1/64 scope global dynamic
> > 
> > mngtmpaddr
> > 
> >       valid_lft 14215sec preferred_lft 14215sec
> >    
> >    inet6 fe80::d263:b4ff:fe00:4dd1/64 scope link
> >    
> >       valid_lft forever preferred_lft forever
> 
> I'm confused that you have uplink and downlink addresses configured on
> the client. Anyway, can you also post 'ip -6 r' from the client?

I have not explicitly configured the addresses, but I have a dnsmasq running on 
the server which might be responsible for that, though I do not see how, I 
have in dnsmasq.conf

# Do router advertisements for all subnets where we're doing DHCPv6                                                                                                                                                                                                                                  
# Unless overriden by ra-stateless, ra-names, et al, the router                                                                                                                                                                                                                                      
# advertisements will have the M and O bits set, so that the clients                                                                                                                                                                                                                                 
# get addresses and configuration from DHCPv6, and the A bit reset, so the                                                                                                                                                                                                                           
# clients don't use SLAAC addresses.                                                                                                                                                                                                                                                                 
enable-ra

# Advertise delegated prefix based on the IPv6 address of eth0.                                                                                                                                                                                                                                      
dhcp-range = ::1,constructor:eth0.7,   ra-stateless, ra-names, 4h


The output you requested on the mohot (endpoint):

rd@mohot:~$ ip -6 r
2a02:8070:898f:e400::/64 dev eth0 proto kernel metric 256 pref medium
2a02:8070:898f:e4f8::/64 dev eth0 proto kernel metric 256 pref medium
2a02:8070:898f:e4f8::/62 dev eth0 proto kernel metric 256 pref medium
fe80::/64 dev eth0 proto kernel metric 256 pref medium
default via fe80::d263:b4ff:fe00:325c dev eth0 proto ra metric 1024 hoplimit 64 
pref medium
default via fe80::e228:6dff:fe43:5776 dev eth0 proto ra metric 1024 hoplimit 
255 pref medium
rd@mohot:~$

I do not understand why there is fe80::e228:6dff:fe43:5776. This is the link 
local address of the ISP router, which does not make sense (?).

but even if I delete entry, I do not get it working: 

root@mohot:~# ip r del default via fe80::e228:6dff:fe43:5776 
root@mohot:~# ip -6 r
2a02:8070:898f:e400::/64 dev eth0 proto kernel metric 256 pref medium
2a02:8070:898f:e4f8::/64 dev eth0 proto kernel metric 256 pref medium
2a02:8070:898f:e4f8::/62 dev eth0 proto kernel metric 256 pref medium
fe80::/64 dev eth0 proto kernel metric 256 pref medium
default via fe80::d263:b4ff:fe00:325c dev eth0 proto ra metric 1024 hoplimit 64 
pref medium
root@mohot:~#

does not change anything (visible) and causes timeouts.

What surprises me is that traceroute6 does not even find home (stretch router)

rd@mohot:~$ traceroute6 2a03:4000:6:52b6::  
traceroute to 2a03:4000:6:52b6:: (2a03:4000:6:52b6::), 30 hops max, 80 byte 
packets
 1  * * *
 2  * * *
 3  * * *

but I am not sure how reliable traceroute is.

A direct connection works well:

rd@mohot:~$ ssh fe80::d263:b4ff:fe00:325c%eth0
Linux home 4.18.0-0.bpo.3-armmp #1 SMP Debian 4.18.20-2~bpo9+1 (2018-12-08) 
armv7l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Sun Jan  6 19:46:41 2019 from fe80::d263:b4ff:fe00:4dd1%eth0.7
rd@home:~$ 



Thanks
Rainer



> 
> best regards
> Ulf


-- 
Rainer Dorsch
http://bokomoko.de/