type: txt
help: "use TCP syn cookies"
default: "enable"
syntax: $(@) in "enable", "disable"; "syn-cookies must be enable or disable"
update: "if [ x$(@) == xenable ]; \
                 then echo 1 > /proc/sys/net/ipv4/tcp_syncookies; \
                 else echo 0 > /proc/sys/net/ipv4/tcp_syncookies; fi"
delete: "echo 1 > /proc/sys/net/ipv4/tcp_syncookies"