OpenWRT – Change TTL (Time to Live) – Hop Limit
In this video, we are going to change the TTL value on OpenWRT. Time to live (TTL) is the amount of time or “hops” that a packet is set to exist inside a network before being discarded by a router.
If you are using USB tethering, there is a specific TTL value that need to be configured. The common TTL value used by the mobile network operator is 65 while the default value on the computer is 128. We need to change this to have a working internet connection or to be able to use the hotspot. Changing TTL does not 100% give you unlimited hotspot with high speed but it depends on your network operator. You can check out videos about OpenWRT USB tethering or OpenWRT LTE module configuration and combine with this tutorial for a better usage.
– Custom Firewall rule:
iptables -t mangle -I POSTROUTING -o wan-interface -j TTL –ttl-set 65
– Edit /etc/sysctl.conf file and add in (in this example TTL 65 is used)
net.ipv4.ip_default_ttl=65
net.ipv6.ip_default_ttl=65
Your can learn more about TTL at:
https://www.cloudflare.com/learning/cdn/glossary/time-to-live-ttl/
Video timeframe:
00:00 – Introduction to TTL changing on OpenWRT
00:17 – Change TTL with Firewall Custom Rule
02:03 – Change TTL by modifying sysctl.conf file
03:11 – Test and final words
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