netdev - Re: socket option IP_MSFILTER questions and observations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 26 Mar 2012 09:34:14 -0700
From:	David Stevens <dlstevens@...ibm.com>
To:	Cedric Jehasse <cedric.jehasse@...tathome.com>
Cc:	netdev@...r.kernel.org, netdev-owner@...r.kernel.org
Subject: Re: socket option IP_MSFILTER questions and observations

> I'm trying to use source specific multicast by setting the IP_MSFILTER 
> socket option. I noticed i need to join the group with IP_ADD_MEMBERSHIP 

> before setting the source filter. This is not the behavior i expected 
> after reading RFC3678.
        RFC3678 doesn't say that an IP_MSFILTER will join a group
automatically. The model is that you join a group once and then
dynamically set the source filters as they change over time.

> A potential issue i'm thinking of with this approach: an IGMP report 
> could be sent after joining a group but before the filter is set.
> Is there a way to prevent this?

        Adding or changing the source filters triggers a new report
but you can use IP_ADD_SOURCE_MEMBERSHIP which does explicitly join
a group with a source filter. In the kernel, this is done with an
"any" join followed by setting a source filter which actually will result
in 2 reports too, if there are no other processes using that group.

                                                        +-DLS

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html