[p2p-hackers] MTU in the real world

[Kendy Kutzner]

On 2005-05-31T06:21:27-0700, Matthew Kaufman wrote:
> > Furthermore, I've read that if you "connect" your UDP socket 
> > to the remote side and then start sending large packets and 
> > backing off slowly, the socket layer will compute the "real" 
> > MTU between two endpoints, and you can obtain it through 
> > "getsockopt".  Do you know of anyone who's tried this, and 
> > the results?
> 
> I'm not aware of any operating system that lets you access Path MTU
> Discovery like this, but I suppose it might exist. Certainly there are some
> which do it for TCP sessions.

Linux:
$ man 7 ip
[...]
SOCKET OPTIONS
[...]
	IP_MTU 
		Retrieve the current known path MTU of the current
		socket.  Only valid when the socket has been connected.
		Returns an integer. Only valid as a getsockopt(2).

Kendy

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