From mboxrd@z Thu Jan 1 00:00:00 1970 From: sean darcy Subject: Re: rate limit SIP INVITES Date: Sat, 26 Sep 2020 16:45:43 -0400 Message-ID: References: Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: netfilter@vger.kernel.org On 9/26/20 4:26 PM, sean darcy wrote: > 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 > > I'm quitting for the day. 4 bits = 1 hex number. 6 ascii characters is 12 hex numbers , or 48 bits.