Subject: Setsockopt

From: vishwas <[email-masked]>
Date: Fri, 25 Sep 98 19:24:00 PDT

Hi Bill,
 Have a small problem in my multimedia apllication.
When I do setsockopt for an IP addr which is a POINTOPOINT link running   
SLIP running on Linux 1.2.1. I get an error message saying "No Such   
Device".. Is setsock opt is supported for serial interfaces..?

Regards
vishwa

---

From: Bill Fenner <[email-masked]>
Date: Fri, 25 Sep 1998 09:45:46 PDT

I assume you mean the IP_ADD_MEMBERSHIP or IP_MULTICAST_IF socket options.
In order to support "unnumbered" interfaces, where the point-to-point
interface has the same address as another interface, some OS's use the
remote address of the interface.  Others use the local address so there
is no way to specify an "unnumbered" interface.

You could use the route to 224/4 (or, in fact, any group) to specify
the default interface for binding or sending multicast.  If you point
the route towards an interface and then use INADDR_ANY for the interface
specification, you should get the same results.

  Bill