From mboxrd@z Thu Jan  1 00:00:00 1970
From: sean darcy <seandarcy2@gmail.com>
Subject: Re: rate limit SIP INVITES
Date: Sat, 26 Sep 2020 16:26:02 -0400
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On 9/26/20 3:10 PM, sean darcy wrote:
> 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
> 
> 

Closer reading of the man page:

# nft add rule filter-asterisk prerouting meta l4proto udp udp dport 
5060 @th,184,96 0x494e56495445 counter
#

The 3rd parameter of the raw expression is bit length (16 * the six 
characters in INVITE , correct?).

Now let's see if it works.

sean