How to add ttl change script to autoload?

Question

linux

After updating linux mint to version 19, I can't add a script to autorun

sudo iptables -t mangle -A POSTROUTING -j TTL --ttl-set 65

I created a file in /etc/init.d/ttl.sh and added some code there, but it didn't work. Then I put it in /etc/profile.d/ttl.sh , but it still doesn't work. Error message pops up when loading

Answer 1

add to /etc/sysctl.conf
net.ipv4.ip_default_ttl=65