ifconfig: Add an allmulti verb

[markj]

Summary

Similar to "promisc", this allows the IFF_ALLMULTI flag to be toggled,
which can be useful for IPv6 neighbour discovery; see PR 233683.

Sponsored by: Klara, Inc.

[glebius]

sbin/ifconfig/ifconfig.8

31

Needs to be bumped.

[zlei]

which can be useful for IPv6 neighbour discovery

@markj I guess you mean help debugging IPv6 ND function ;)

Looks good to me.

[ae]

I think you need to modify IFF_CANTCHANGE in sys/net/if.h

[markj]

In D46525#1060565, @zlei wrote:

which can be useful for IPv6 neighbour discovery

@markj I guess you mean help debugging IPv6 ND function ;)

Looks good to me.

The use-case which motivated this is neighbour discover over netmap, where the kernel doesn't know which multicast addresses to subscribe to.

In D46525#1060625, @ae wrote:

I think you need to modify IFF_CANTCHANGE in sys/net/if.h

IMO that is not quite right, per the comments in D46524.

[markj]

Toggle IFF_PALLMULTI instead of IFF_ALLMULTI, to match IFF_PROMISC handling.

[zlei]

I like this.

[zlei]

In D46525#1060648, @markj wrote:

In D46525#1060565, @zlei wrote:

which can be useful for IPv6 neighbour discovery

@markj I guess you mean help debugging IPv6 ND function ;)

Looks good to me.

The use-case which motivated this is neighbour discover over netmap, where the kernel doesn't know which multicast addresses to subscribe to.

I'd support if you can include that in the final commit message :)

In D46525#1060625, @ae wrote:

I think you need to modify IFF_CANTCHANGE in sys/net/if.h

IMO that is not quite right, per the comments in D46524.

[markj]

In D46525#1061131, @zlei wrote:

In D46525#1060648, @markj wrote:

In D46525#1060565, @zlei wrote:

which can be useful for IPv6 neighbour discovery

@markj I guess you mean help debugging IPv6 ND function ;)

Looks good to me.

The use-case which motivated this is neighbour discover over netmap, where the kernel doesn't know which multicast addresses to subscribe to.

I'd support if you can include that in the final commit message :)

Thanks for taking a look. Certainly, my original description is basically useless. :(