Re: SOCK_RAW does not receive broadcast (with VLAN unless PROMISC)

From: Patrick McHardy
Date: Wed Jun 10 2009 - 10:33:20 EST

Again, please don't top post.

Gil Beniamini wrote:
My application is a "proxy" and need to support few VLANs (for example vlan 24).
I define all vlans on interface 'eth0' which is my "out i/f", while
the other interface 'eth1' (used as "in i/f") I use with PF_PACKET /
SOCK_RAW in order to handle VLANs by my application (starting with
"arp broadcast").
When I try to define the same (relevant VLAN) on eth1 (inorder to
check your suggestion), I get "Error: trying to add VLAN #24 to IF
-:eth1:- error: file exist".
It seems that linux does not allow to define the same VLAN # on more
than a single i/f?!

No, that has got to be a mistake. You can use the same ID once
per underlying device:

# ip -d link list

4: vlan0@dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN
link/ether d6:1f:c0:bd:b2:ec brd ff:ff:ff:ff:ff:ff
vlan id 1000 <REORDER_HDR>
6: vlan1@dummy1: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN
link/ether 8a:17:13:5d:87:1a brd ff:ff:ff:ff:ff:ff
vlan id 1000 <REORDER_HDR>

If it doesn't work for you, please post the full commands
and ip -d link list output you used.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at