What is TTL?

• TTL (Time To Live) is a special indicator in the header of an IP packet that determines the lifetime of the packet. It is needed to prevent loops in the network (So that the packet does not run in a circle, from one router to another).

• TTL is a number, in the range from 0 to 255, which decreases by 1 when a packet passes through 1 router.

• If TTL becomes 0, this packet is discarded.

• The usual initial value of TTL=64 (Linux, Mac, Android, iOS), TTL=128 (Windows). 

• TTL control is often used by providers. For example, to prohibit the distribution of mobile Internet to other devices.  The TTL from the devices connected to the phone will be 1 less than expected. This allows you to identify the devices used in modem mode and, if necessary, block access for them.