XPost: comp.os.linux.networking
From: grahn+nntp@snipabacken.se
On Sun, 2011-05-22, Mark Hobley wrote:
> On Sun, 22 May 2011 11:31:25 +0000, Jorgen Grahn wrote:
>
>> On Sun, 2011-05-22, Mark Hobley wrote: ...
>>> I'll try dropping another 12 bytes off the ip route command and retest:
>>>
>>> ip route change default via 10.0.0.1 mtu lock 1400
>>>
>>> Am I right in that the below datagram is wrong, because the mss is
>>> 1460, which is above the value of the mtu in the routing table?
>>> Shouldn't the value of the mtu have been factored in here, and a new
>>> mss calculated based on the mtu?
>>>
>>> 03:43:04.320740 IP venus.markhobley.yi.org.52201 >
>>> news.eternal-september.org.nntp: Flags [S], seq 2304145392, win 14600,
>>> options [mss 1460,sackOK,TS val 47122576 ecr 0,nop,wscale 5], length 0
>>
>> Yes, that seems wrong too. I have only messed with that once, as an
>> experiment, but I am pretty sure my TCP stack understood it and set mss
>> in the SYN accordingly. (I used 'route ... mss N' to do it, not ip(8),
>> but that shouldn't matter.)
>
> Hmmm. So if the datagram is wrong, then we have a bug. Presumably this is
> a kernel bug, because it has been working for a couple of months before I
> upgraded the kernel. Or could it be a library bug? I might have upgraded
> some libraries, for the purpose of being able to use the new kernel.
It seems to me it's more likely that you're doing something wrong --
people would immediately notice if these parts of the Linux kernel
broke! Is it the right route? Are there others? What does route -ne say?
I also can't help wondering if you have caused all these problems
somehow. If the ISP breaks things like this, it's commercial suicide
-- unless they somehow manage to keep Windows unaffected ...
/Jorgen
--
// Jorgen Grahn O o .
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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