Golang : How to check if IP address is in range
For security purpose, sometimes a server can only accept connection from clients that are trusted and of certain IP addresses. This tutorial will demonstrate how to use bytes.Compare() function to check to see if an incoming IP address is within the trusted range.
checkip.go
package main
import (
"net"
"bytes"
"fmt"
)
var (
// specify the range of trusted IP addresses
start = net.ParseIP("198.162.1.100")
end = net.ParseIP("198.162.1.199")
)
func checkIP(ip string) bool {
//sanity check
input := net.ParseIP(ip)
if input.To4() == nil {
fmt.Printf("%v is not a valid IPv4 address\n", input)
return false
}
if bytes.Compare(input, start) >= 0 && bytes.Compare(input, end) <= 0 {
fmt.Printf("%v is between %v and %v\n", input, start, end)
return true
}
fmt.Printf("%v is NOT between %v and %v\n", input, start, end)
return false
}
func main() {
fmt.Println(checkIP("216.14.49.185"))
fmt.Println(checkIP("1.2.3.4"))
fmt.Println(checkIP("198.162.1.102"))
fmt.Println(checkIP("1::16"))
}
Output :
216.14.49.185 is NOT between 198.162.1.100 and 198.162.1.199
false
1.2.3.4 is NOT between 198.162.1.100 and 198.162.1.199
false
198.162.1.102 is between 198.162.1.100 and 198.162.1.199
true
1::16 is not an IPv4 address
false
Reference :
By Adam Ng
IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.
Advertisement
Tutorials
+18.3k Golang : Example for DSA(Digital Signature Algorithm) package functions
+19.9k Golang : Sort and reverse sort a slice of strings
+12.6k Golang : Reverse IP address for reverse DNS lookup example
+5.8k Golang : Reverse by word
+25.6k Golang : dial tcp: too many colons in address
+8.8k Golang : List available AWS regions
+4.7k Python : Print unicode escape characters and string
+15k Golang : convert string or integer to big.Int type
+16.2k Golang : delete and modify XML file content
+18.6k Golang : Set or Add HTTP Request Headers
+18.2k Golang : How to run your code only once with sync.Once object
+15.5k Golang : read gzipped http response