[NETFILTER]: nf_conntrack: add NetBIOS name service helper port

Add nf_conntrack port of the NetBIOS name service conntrack helper.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index bd50897d8fb..d1a365d83c5 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -194,6 +194,25 @@ config NF_CONNTRACK_IRC
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NF_CONNTRACK_NETBIOS_NS
+	tristate "NetBIOS name service protocol support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	help
+	  NetBIOS name service requests are sent as broadcast messages from an
+	  unprivileged port and responded to with unicast messages to the
+	  same port. This make them hard to firewall properly because connection
+	  tracking doesn't deal with broadcasts. This helper tracks locally
+	  originating NetBIOS name service requests and the corresponding
+	  responses. It relies on correct IP address configuration, specifically
+	  netmask and broadcast address. When properly configured, the output
+	  of "ip address show" should look similar to this:
+
+	  $ ip -4 address show eth0
+	  4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
+	      inet 172.16.2.252/24 brd 172.16.2.255 scope global eth0
+
+	  To compile it as a module, choose M here.  If unsure, say N.
+
 config NF_CT_NETLINK
 	tristate 'Connection tracking netlink interface (EXPERIMENTAL)'
 	depends on EXPERIMENTAL && NF_CONNTRACK && NETFILTER_NETLINK