Re: switch networkconnection without breaking sessions

From: Mihai Osian (zzz_at_zzz.com)
Date: 07/14/05 

Date: Thu, 14 Jul 2005 13:31:26 +0200

peter pilsl wrote:

>
> My laptop has two networkcards (ethernet, wlan). I connect via wlan,
> open loads of ssh-session and xterms on other machines and finally
> come back to my desk and want to connect via ethernet. So I plug in
> ethernet and perform
>
> ifconfig wlan0 down
> dhclient eth0
>
> within one second I'm connected to the internet via ethernet, but all
> my connections are lost.
>
> What is the trick to keep the sessions alive?
>
> * screen - somehow I never got used to it

  Well, get use to it.

> * same ip - give the same mac to wlan and ethernet to get the same ip
> on both cards and hope this will keep the sessions open. This somehow
> doesnt sound smart to me. To networkcards with the same MAC on the
> same machine sure pegs for troubles ;)
>
It won't work. First of all I'm afraid your TCP connections will be
terminated on "ifconfig down" so there won't be anything to resume.
Second, a TCP/IP session is not all about MAC/IP addresses, it's about
data structures in the kernel (like packet sequence number, transmission
buffers, etc). Forget it, it's not possible.

Mihai

> thnx,
> peter

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