Adjust Maximum Segment Size?

[Stefan Lambrev]

Ermal Luçi wrote:
> On Tue, May 27, 2008 at 8:04 PM, Stefan Lambrev
> <stefan.lambrev at moneybookers.com> wrote:
>   
>> Greetings,
>>
>> Alexander Motin wrote:
>>     
>>> Stefan Lambrev wrote:
>>>       
>>>>> Yes, You can with ng_tcpmss
>>>>>           
>>>> Isn't it doable only with ipfw/divert when using ng_tcpmss?
>>>> I have and some concerns about performance too ..
>>>>         
>>> There are several ways to inject packet to ng_tcpmss:
>>>  - ipfw + divert + ng_ksocket. It should be faster then usual user-level
>>> implementation
>>>  - ipfw + netgraph as described in ng_tcpmss(4)
>>>  - use ng_tcpmss directly in some complicated netgraph setup. For example,
>>> mpd is able to use it. This is probably the fastest and easiest way, but
>>> only for some setups.
>>>       
>> Thanks for all ideas.
>> I think I'll try the route -mtu feature.
>> Looks like easier for implementation and testing. :)
>> Anyway it will be good if we have such feature in the base system.
>> It shouldn't be very difficult? :)
>>
>> --
>>     
>
> Actually converting ng_tcpmss to pfil(9) should be easy.
>   
I'm thinking about adding additional checks in tcp_mss() and 
tcp_mssopt() - both in sys/netinet/tcp_input.c
plus two sysctl entries for max mss and max mss IPv6.
Does it sound like a reasonable solution or I'm missing something?

P.S. One of the things that bothers me is that pf uses it's own 
pf_get_mss() and pf_calc_mss()
and they should be fixed accordingly?

-- 

Best Wishes,
Stefan Lambrev
ICQ# 24134177