It's an IPv4 address expressed as a 4-byte integer instead of four separate decimal octets. 172.217.23.110 is an IP belonging to Google.
172<<24 + 217<<16 + 23<<8 + 110 = 2899908462
172<<24 + 217<<16 + 23<<8 + 110 = 2899908462
Saves 4 whole keystrokes if you quickly want to ping something to test connectivity.
So if you own some 31.x block, you could have a phone number which matches your IP.
[0] https://en.wikipedia.org/wiki/Universal_Personal_Telecommuni...
The US phone system had such a service for a few years (area code 500 iirc). It had so little uptake that it was shut down.
I think I'm wrong, it was about the 10-digit Dutch numbers.
#!/bin/ksh
Die() {
echo Bad IP
exit 1
}
[ $# = 1 ] || Die
[ ${1%%?*.?*.?*.?*} ] && Die
I=$1
until [ ${#I} = 0 ]
do
J=${I#[0-9.]}
[ ${#I} = ${#J} ] && Die
I=$J
done
I=$1.
typeset -ui N=0
while [ $I ]
do
J=${I%%.*}
I=${I#$J.}
[ $((J>>8)) = 0 ] || Die
N=$(( (N<<8) + J ))
done
echo $N
# End