Hi I have been using the tap-win32 driver with multicast in TUN mode. In its current version the tap-win32 driver blocks multicast packets in AdapterTransmit as it only allows unicast packets. I have written a patch for the driver to allow multicast packets through the driver which works for me which I wanted to share (although IGMPv2 doesn't seem to get through - IGMPv3 does...). I hope someone find it useful and that some form of it might find its way into 2.2 (so I don't have to patch the driver when new versions are released ;) ) (Could not find a way to attach the patch, so I am including it here) [code] Index: macinfo.h =================================================================== --- macinfo.h (revision 6688) +++ macinfo.h (working copy) @@ -34,5 +34,6 @@ #define COPY_MAC(dest, src) NdisMoveMemory ((dest), (src), sizeof (MACADDR)) #define CLEAR_MAC(dest) NdisZeroMemory ((dest), sizeof (MACADDR)) #define MAC_EQUAL(a,b) (memcmp ((a), (b), sizeof (MACADDR)) == 0) +#define MAC_IPv4_MULTICAST(a) (a[0] == 0x01 && a[1] == 0x00 && a[2] == 0x5e) #endif Index: tapdrvr.c =================================================================== --- tapdrvr.c (revision 6826) +++ tapdrvr.c (working copy) @@ -1104,8 +1104,8 @@ case OID_GEN_CURRENT_PACKET_FILTER: l_Query.m_Long = - (NDIS_PACKET_TYPE_ALL_LOCAL | - NDIS_PACKET_TYPE_BROADCAST | + (NDIS_PACKET_TYPE_ALL_LOCAL | NDIS_PACKET_TYPE_BROADCAST + NDIS_PACKET_TYPE_MULTICAST | NDIS_PACKET_TYPE_ALL_MULTICAST | NDIS_PACKET_TYPE_DIRECTED | NDIS_PACKET_TYPE_ALL_FUNCTIONAL); break; @@ -1582,6 +1582,20 @@ return TRUE; // all fine } +BOOLEAN +IPv4AcceptMulticast(PETH_HEADER p_Header, PETH_HEADER p_AdapterHeader) +{ + return (MAC_IPv4_MULTICAST(p_Header->dest) && + MAC_EQUAL(p_Header->src, p_AdapterHeader->src) && + p_Header->proto == p_AdapterHeader->proto); +} + +BOOLEAN +IPv4AcceptUnicast(PETH_HEADER p_Header, PETH_HEADER p_AdapterHeader) +{ + return (memcmp (p_Header, p_AdapterHeader, ETHERNET_HEADER_SIZE) == 0); +} + //==================================================================== // Adapter Transmission //==================================================================== @@ -1759,10 +1773,10 @@ m_TapToUser, ETHERNET_HEADER_SIZE)) - goto no_queue; + // Accept directed packets and multicast packets, but not broadcasts + if(!IPv4AcceptMulticast(e, &l_Adapter->m_TapToUser) && + !IPv4AcceptUnicast(e, &l_Adapter->m_TapToUser)) + goto no_queue; // Packet looks like IPv4, queue it. l_PacketBuffer->m_SizeFlags |= TP_TUN; [/code] Regards Lau Bakman

Multicast support in tap-win32 (with patch)

bakman

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cutty201

This looks awesome, and in line with some goals I am trying to accomplish with OpenVPN. I see you only made one post, and there are no replies...did this make it in the latest build? I am having some issues with multicast over TUN atm, I am just starting to work with the routing, but I am having a hard time finding data on IGMP and how its handle on OpenWRT and DD-WRT. If you're still working with multicast over OpenVPN, I'd love to swap notes. 🙂