rate limit SIP INVITES

[sean darcy <seandarcy2@gmail.com>]

nftables-0.9.6

I'm running a VOIP server. There are lots of script kiddies who will 
bang away with 10/sec SIP INVITES or REGISTERS .

In iptables you can match on the string:

-A SIP   -i eth0 -p udp -m udp --dport 5060 -m string   --string 
"INVITE" --algo bm --from 23 --to 28 -m comment --comment "Catch SIP 
INVITEs" -j SIPINVITE

-A SIP   -i eth0 -p udp -m udp --dport 5060 -m string   --string 
"REGISTER" --algo bm --from 23 --to 30 -m comment --comment "Catch SIP 
REGISTERs" -j SIPREGISTER

I'm looking at RAW to do the same:

meta l4proto udp udp dport 5060 @th,184,224 0x494e56495445 counter

where 184 = 23*8, and 224 = 28*8. INVITE is 0x494e56495445 in hex

I have a prerouting chain:

table ip filter-asterisk {
	chain output-asterisk {
		..................
	}

	chain prerouting {
		type filter hook prerouting priority raw; policy accept;
	}
}

but no joy when I try to add the rule:

nft add rule filter-asterisk prerouting meta l4proto udp udp dport 5060 
@th,184,224 0x494e56495445 counter
Error: Could not process rule: Value too large for defined data type
add rule filter-asterisk prerouting meta l4proto udp udp dport 5060 
@th,184,224 0x494e56495445 counter
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Any help appreciated.

sean