How do we get public IP in golang? Method req.Header.Get("X-Forwarded-For") returns array of IPs. How do we identify which one is public and which on internal? Is there any other method to fetch public(external) IP?
The following IP blocks are reserved for private IP addresses.
Class Starting IPAddress Ending IP Address # of Hosts
A 10.0.0.0 10.255.255.255 16,777,216
B 172.16.0.0 172.31.255.255 1,048,576
C 192.168.0.0 192.168.255.255 65,536
Link-local-u 169.254.0.0 169.254.255.255 65,536
Link-local-m 224.0.0.0 224.0.0.255 256
Local 127.0.0.0 127.255.255.255 16777216
You may write a function that checks for if the ip comes under these
Here is an attempt to do the same,the code below is not handling ipv6 please add if needed
func IsPublicIP(IP net.IP) bool {
if IP.IsLoopback() || IP.IsLinkLocalMulticast() || IP.IsLinkLocalUnicast() {
return false
}
if ip4 := IP.To4(); ip4 != nil {
switch {
case ip4[0] == 10:
return false
case ip4[0] == 172 && ip4[1] >= 16 && ip4[1] <= 31:
return false
case ip4[0] == 192 && ip4[1] == 168:
return false
default:
return true
}
}
return false
}
Here is play link
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