[Chilli] Best way to enforce MTU 1480?

[Ben West]

Thanks for the response, David.  Would you happen to know correct syntax
for deploying such an iptables rules with coovachilli v1.3.0 under OpenWRT
AA?  I.e. presumably within a connup/conndown or macup/macdown script?

I'm not immediately sure what chain such an iptables rule should be
appended to.

iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS
--clamp-mss-to-pmtu



On Thu, Mar 27, 2014 at 3:52 PM, David Bird <dbird at google.com> wrote:

> The MTU option will send the MTU value in DHCP, but doesn't mean it's
> always respected. You might refer to
> http://lartc.org/howto/lartc.cookbook.mtu-mss.html
>
>
> On Thu, Mar 27, 2014 at 12:30 PM, Ben West <ben at gowasabi.net> wrote:
>
>> I'm running coovachilli v1.3.0 under OpenWRT AA on Ubiquiti Nanostation
>> gear, with only 32Mbytes of RAM.  Since these are nodes in a mesh managed
>> by OLSR, I need to enforce MTU=1480 for all client sessions authorized by
>> chilli.
>>
>> From the online Changlog, it appears I can do this by adding a parameter
>> to the start-up command in coovachilli's init script:
>>
>> /usr/sbin/chilli --mtu 1480
>>
>> However, the tap interface which I believe is what chilli sets up to
>> manage bandwidth throttling on client sessions still reports MTU 1500:
>>
>> tun0      Link encap:UNSPEC  HWaddr
>> 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
>>           inet addr:101.232.44.1  P-t-P:101.232.44.1  Mask:255.255.255.0
>>           UP POINTOPOINT RUNNING  MTU:1500  Metric:1
>>           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>>           collisions:0 txqueuelen:100
>>           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
>>
>> ... where 101.232.44.1 is the NAP IP of the device where I quoted this
>> from.
>>
>> Is there a way I can ensure proper MTU settings on chilli client sessions?
>>
>> --
>> Ben West
>> http://gowasabi.net
>> ben at gowasabi.net
>> 314-246-9434
>>
>> _______________________________________________
>> Chilli mailing list
>> Chilli at coova.org
>> http://lists.coova.org/cgi-bin/mailman/listinfo/chilli
>>
>>
>


-- 
Ben West
http://gowasabi.net
ben at gowasabi.net
314-246-9434
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