[Spread-users] Trouble binding to specific interface

Jonathan Stanton jonathan at cnds.jhu.edu
Fri Nov 16 15:45:37 EST 2001

On Fri, Nov 16, 2001 at 12:24:49PM -0800, Dave Parker wrote:
> Jonathan Stanton wrote:
> > > from lsof: spread    7168     root    6u  IPv4      22871
> > > UDP *:1083
> > >
> > > Is there an option for whatever that is too?
> > 
> > I think this is the UDP sending socket that we create to send broadcasts
> > (and other messages) on. We do not bind it to a specific port, but rather
> > let the kernel assign it a random port, as we do not care which one it
> > uses. I guess it is picking 1083 on your system.
> Does this mean I'll be generating traffic on any interface the box has
> running? Or will that traffic restrict itself to the network(s) I've
> specified in the conf file for control and daemon traffic?

The interfaces that the messages will be sent out depend on the routing
tables of the kernel. Just like any normal packet that is sent without
binding to specify the source address, it will be assigned the source
address by the kernel based on which interface the packet is routed out of.
So, I think Spread will only send traffic destined for ip addresses you
configure, so the kernel should only send the traffic out of those

But, I know there are a number of quirks with various kernels and how they
handle broadcast/multicast traffic, so there might be some that send it to
more networks then they should.


Jonathan R. Stanton         jonathan at cs.jhu.edu
Dept. of Computer Science   
Johns Hopkins University    

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