I did write an ebtables module to work around this 802.11 3 address problem - it performed L2 NAT on DHCP, ARP and IP packets, so allowing an 802.11 client be added to a bridge. It was released under GPL about 5 years ago (from my previous company Instant802/Devicescape), but I can't find the source anymore!!! Simon On 05/19/2010 12:20 PM, John W. Linville wrote: > On Wed, May 19, 2010 at 10:15:35AM -0700, Umar Qureshey wrote: > >> What about bridging in Ad-Hoc mode? Would that technically work? > > No. > >> I guess what I am trying to figure out is why bridging would work in WDS mode? What is it about that mode that allows bridging to work? > > It has to do with the MAC-layer addressing on wireless LANs. Wireless > frames can use 2, 3, or 4 MAC addresses to identify the transmitter, > receiver, sender, and destination. For most frames and most modes, > 3 MAC addresses are used. The FromDS and ToDS bits in the header > are used to allow one of the MAC address fields to specify either > the transmitter and sender or the destination and receiver. This is > sufficient for non-bridged cases since the wireless station is either > an endpoint of the communication or possibly a router (and therefore > a Layer-2 endpoint). > > WDS (or 4 address) mode removes this limitation by using 4 MAC > addresses to identify all 4 roles independently. So, the wireless > station is able to forward frames received off the air to the > appropriate destination with the correct sender information intact. > > mac80211-based devices can have interfaces created with support for > 4 address mode using the iw command. For this to work, your AP has > to be willing to accept and forward those frames appropriately -- > some do, others don't. This is only supported for "managed" mode > interfaces AFAIK. > >> If one were to try to modify the kernel code to allow MAC-level NAT, which area of the kernel code would one look at? > > netfilter -- I thought there was already some ebtables code to > do this...? > > John _______________________________________________ Bridge mailing list Bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/bridge
