Golang : Get host name or domain name from IP address
Thought this tutorial could be a good compliment to previous tutorial on how to find network of an IP address. Basically, what this small Golang program does is to scan and try to map a given IP address to its equivalent domain/host name... a reverse of translating domain name to IP addresses.
Here you go :
package main
import (
"fmt"
"net"
"os"
"strconv"
"strings"
"time"
)
func getHostName(host chan string, ipAddress string, n int) {
ip := ipAddress + strconv.Itoa(n)
if addr, err := net.LookupAddr(ip); err == nil {
host <- ip + " -" + addr[0]
} else {
host <- "err " + err.Error()
}
}
func main() {
if len(os.Args) != 2 {
fmt.Fprintf(os.Stderr, "Usage: %s IP-address\n", os.Args[0])
os.Exit(1)
}
ipAddr := os.Args[1]
segments := strings.SplitAfter(ipAddr, ".")
ipAddress := segments[0] + segments[1] + segments[2]
haveHost := make(chan string)
max := 55
for counter := 0; counter < max; counter++ {
go getHostName(haveHost, ipAddress, counter)
}
count := 0
timeOut := time.After(5 * time.Second)
lookups:
for {
select {
case host := <-haveHost:
fmt.Println("host :" + host)
case <-timeOut:
fmt.Println("time out")
break lookups
}
count++
if count == max {
break
}
}
fmt.Println("Network scanned")
}
Sample output :
$ ./netinterfaces 54.255.183.119
host :54.255.183.0 -ec2-54-255-183-0.ap-southeast-1.compute.amazonaws.com.
host :54.255.183.5 -ec2-54-255-183-5.ap-southeast-1.compute.amazonaws.com.
host :54.255.183.26 -ec2-54-255-183-26.ap-southeast-1.compute.amazonaws.com.
host :54.255.183.28 -ec2-54-255-183-28.ap-southeast-1.compute.amazonaws.com.
host :54.255.183.44 -ec2-54-255-183-44.ap-southeast-1.compute.amazonaws.com.
host :54.255.183.2 -ec2-54-255-183-2.ap-southeast-1.compute.amazonaws.com.
References :
https://www.socketloop.com/tutorials/golang-find-network-of-an-ip-address
See also : Golang : Find network of an IP address
By Adam Ng
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