FreeBSD 7.0 and pf

[Girish Venkatachalam]

On 07:56:48 Mar 19, Norman Maurer wrote:
> Hi all,
> 
> im using freebsd 7.0  + gif interfaces + racoon + pf to filter stuff on
> my box. After upgrading to freebsd 7.0 I see some strange behavior. I
> see packets get dropped because of bad hdr length. The problems only
> seems to happen on traffic between the local nets and nets routed via
> ipsec. Here is a tcpdump snipped:
> 
> block in on em5: 192.168.175.4.1107 > 192.168.116.6.22:  tcp 544 [bad
> hdr length 12 - too short, < 20]
> 
> gif interface:
> gif5: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1402
>         tunnel inet 213.157.17.67 --> 213.23.198.131
>         inet 192.168.116.1 --> 192.168.175.1 netmask 0xffffff00 
> 
> 
> Any help is welcome.

A TCP header can never be less than 20 bytes.

And 12 is odd since all headers are a multiple of 4 bytes (word
boundary).

Check your MTU of the PPPoE/PPPoA/Ethernet/WiFi or whatever datalink
layer. I bet there is a problem there.

Best,
Girish

-- 
"unix soi qui mal y pense"

UNIX to him who evil thinks

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