How to change the default TTL of TCP/IP packets?

Solution 1:

To change the default TTL of TCP/IP packets sent from your Linux computer you can run the following command:

sudo sysctl -w net.ipv4.ip_default_ttl=129

Or:

echo 129 | sudo tee /proc/sys/net/ipv4/ip_default_ttl

Or:

sudo bash -c 'echo 129 > /proc/sys/net/ipv4/ip_default_ttl'

But you have to run one of those commands whenever the computer boots. To make this setting persistent across reboots you could append the following line to the file /etc/sysctl.conf:

net.ipv4.ip_default_ttl=129

You should do the same with ipv6 instead of ipv4 if you want to change the settings for ipv6 as well.