# IPv6 link-local & tcpdump using IPv6



## Priyaamaresh (Jun 12, 2012)

Hi,

Am using FreeBSD7.4/i386. I configured IPv6 by adding the following to /etc/rc.conf


```
ipv6_enable="YES"
ipv6_ifconfig_bce0="2010::5ef3:fcff:feb6:59bc"
ipv6_defaultrouter="2010::5ef3:fcff:feb6:1"
ipv6_network_interfaces="bce0"
ipv6_default_interface="bce0"
```

Now my problems are:

How to make IPv6 link-local address possible? I tried with [cmd=]sysctl -w net.inet6.ip6.auto_linklocal=1[/cmd]
Because should use link-local address in TAHI testsuite. But it is using IPv4 address rather than link-local IPv6 address as its source and destination. Is the presence of Global IPv6 is the cause of this issue? How to make replace that IPv4 with IPv6 link-local address?
How to dump IPv6 packets? I tried with [cmd=]tcpdump -i bce0[/cmd] was very fine since uses IPv4. When I tried with IPv6 

```
# tcpdump -i bce0 -s 512 -vv ip6 or proto ipv6
tcpdump: listening on bce0, link-type EN10MB (Ethernet), capture size 512 bytes
```


So please help me to make link-local address communication possible and dump IPv6 packets into the other host(AIX). If am wrong in concepts in what I have mentioned, Do correct me.


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## SirDice (Jun 12, 2012)

Priyaamaresh said:
			
		

> i) How to make IPv6 link-local address possible?


They are created automatically.



> How to make replace that IPv4 with IPv6 link-local address?


Configure your test suite.




> ii) How to dump IPv6 packets?
> I tried with "tcpdump -i bce0" was very fine since uses IPv4



That command dumps both IPv4 and IPv6.



> When I tried with IPv6
> 
> ```
> # tcpdump -i bce0 -s 512 -vv ip6 or proto ipv6
> ...


If that doesn't show anything there simply isn't any IPv6 traffic.


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