Yes, or if you prefer you can simply extend "bridge" forwarding logic to copy every packet to an additional TAP port. Copying a packet in netmap is just a matter of initialize the next struct netmap_slot in the destination (TAP) netmap ring, memcpy() the packet payload and incrementing ring->cur/ring->head (then you need to TXSYNC or poll() at the end of the batch. In any case the application will work on both FreeBSD and Linux, as the API is the same.
You may also find useful to look at the netmap tutorial, to see more examples and explanations: https://github.com/vmaffione/netmap-tutorial Cheers, Vincenzo 2017-12-15 6:58 GMT+01:00 Jim Thompson <j...@netgate.com>: > > > > On Dec 14, 2017, at 12:00 PM, Ming Fu <ming...@esentire.com> wrote: > > > > Hi, > > > > I am trying to explore the possibility to build a network SPAN/TAP from > netmap. Similar to the bridge sample, but all packet going through the > bridge also get copied to a SPAN port. How do I duplicate or clone an > incoming packet and send the original to bridge peer and the cloned one to > the SPAN port? Is there an API like FreeBsd m_copypacket() for netmap? > Would it work for Linux as well? > > > > Thanks > > Ming > > Ming, > > I’d look at adapting netmap monitors. > > https://github.com/luigirizzo/netmap/blob/master/sys/dev/ > netmap/netmap_monitor.c > > For the rest of the solution, look at netmap_user.h, where it explains how > to open a port in monitor mode. > > https://github.com/luigirizzo/netmap/blob/master/sys/net/netmap_user.h > > Essentially, once you have an active netmap port e.g. netmap:ix0, you can > sniff the traffic by opening additional netmap ports > named netmap:ix0/r (for rx traffic) or netmap:ix0/t (for tx) or even > netmap:ix0/rt (for both tx and rx) > > The rest of the code (to inject frames back down another interface) can be > lifted from the bridge sample. > > You could also look at SF-TAP. http://sf-tap.github.io > > Jim > > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org" > -- Vincenzo Maffione _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
