[NETFILTER]: nf_conntrack/nf_nat: add TFTP helper port

Add IPv4 and IPv6 capable nf_conntrack port of the TFTP conntrack/NAT helper.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index e738911..e0deac1 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -248,6 +248,17 @@
 
 	  To compile it as a module, choose M here.  If unsure, say N.
 
+config NF_CONNTRACK_TFTP
+	tristate "TFTP protocol support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && NF_CONNTRACK
+	help
+	  TFTP connection tracking helper, this is required depending
+	  on how restrictive your ruleset is.
+	  If you are using a tftp client behind -j SNAT or -j MASQUERADING
+	  you will need this.
+
+	  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