Netfilter nf_tables SYNPROXY expression support

modulename: nft_synproxy.ko

configname: CONFIG_NFT_SYNPROXY

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Network packet filtering framework (Netfilter)
└─>Core Netfilter Configuration
└─>Netfilter nf_tables SYNPROXY expression support
In linux kernel since version 5.1 (release Date: 2019-05-05)  
The SYNPROXY expression allows you to intercept TCP connections and
establish them using syncookies before they are passed on to the
server. This allows to avoid conntrack and server resource usage
during SYN-flood attacks.

source code: