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List:       freeradius-devel
Subject:    Re: "Error receiving packet"
From:       "Alan DeKok" <aland () ox ! org>
Date:       2003-02-22 17:09:27
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Alan Curry <pacman@TheWorld.com> awoke from slumber and wrote:
> It's Linux following RFC1122 section 4.1.3.3.
> 
> quoth the standard:
...
> >         The application is also
> >         responsible to avoid confusion from a delayed ICMP
> >         error message resulting from an earlier use of the same
> >         port(s).
> 
> The last sentence almost seems to be a prophecy about this particular
> freeradius error.

  It's talking about different applications accidentally re-using UDP
ports, where delayed ICMP messages are returned.  That's a little
different than what's happening here.

> You may call this a stupid mandate from the RFC, properly ignored. But it's
> STD3, and it's a MUST. And it was written before Linux existed. Spread the
> blame around a little.

  http://www.unixguide.net/network/socketfaq/5.4.shtml

  Remember that your socket must be "connected" in order to receive the
  ICMP errors.  I've been told, and Alan Cox has verified that Linux
  will return them on "unconnected" sockets.  This may cause porting
  problems if your application isn't ready for it, so Alan tells me
  they've added a SO_BSDCOMPAT flag which can be set for Linux kernels
  after 2.0.0.


  Alan DeKok.

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