Get client IP Address in Go
Knowing who is accessing your web server can be useful for tracking a user's activity. In this tutorial, we will learn how to get client IP address in Go.
To get the IP address of a client, just use
ip,_,_ := net.SplitHostPort(r.RemoteAddr)
However, sometimes the user access your web server via a proxy or load balancer ( such as in cloud hosting etc ) and the above code will give you the IP address of the proxy or load balancer.
To get the real IP address of the client, you can get the HTTP Request header information "X-Forwarded-For (XFF)"
fmt.Fprintf(w,"X-Forwarded-For :" + r.Header.Get("X-FORWARDED-FOR"));
This is the full code example that you can execute in your web server and test out with your web browser or curl.
client_ip.go
package main
import (
"fmt"
"net/http"
"net"
)
func IndexPage(w http.ResponseWriter, r *http.Request) {
// get client ip address
ip,_,_ := net.SplitHostPort(r.RemoteAddr)
// print out the ip address
fmt.Fprintf(w,ip + "\n\n")
// sometimes, the user acccess the web server via a proxy or load balancer.
// The above IP address will be the IP address of the proxy or load balancer and not the user's machine.
// let's get the request HTTP header "X-Forwarded-For (XFF)"
// if the value returned is not null, then this is the real IP address of the user.
fmt.Fprintf(w,"X-Forwarded-For :" + r.Header.Get("X-FORWARDED-FOR"));
}
func main() {
http.HandleFunc("/", IndexPage)
http.ListenAndServe(":8080", nil)
}
References:
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
+4.9k Swift : Get substring with rangeOfString() function example
+19.6k Golang : Saving private and public key to files
+17.5k Golang : Write file with io.WriteString
+20.8k Golang : Setting up/configure AWS credentials with official aws-sdk-go
+6.3k Golang : Transform lisp or spinal case to Pascal case example
+4.8k Python : Print unicode escape characters and string
+13.2k Golang : Check if a file exist or not
+21.5k Golang : Convert Unix timestamp to UTC timestamp
+6.5k Golang : File system scanning
+11k Golang : Detect user location with HTML5 geo-location
+35.4k Golang : Display float in 2 decimal points and rounding up or down
+31.2k Golang : Convert []string to []byte examples