查詢方法 sysctl -ar '.rp_filter' 或 cat /usr/lib/sysctl.d/50-default.conf | grep net.ipv4.conf kernel 說明 https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt rp_filter - INTEGER 0 - No source validation. 1 - Strict mode as defined in RFC3704 Strict Reverse Path Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded. 2 - Loose mode as