On Sat, Sep 26, 2020 at 03:10:24PM -0400, 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: nft add rule x y udp dport 5060 @th,64,48 0x494e56495445 counter @th => transport header 64 => from bit number 64 (8 bytes after the UDP header) 48 => extract 48 bits (6 bytes for INVITE)
