Golang : Find network service name from given port and protocol

In this tutorial, we will learn how to discover the list of available network services on a machine. This method can be useful in developing network application that needs to probe a machine network configuration first before starting the main program.

The example program below uses the https://godoc.org/honnef.co/go/netdb package to discover the available network services. It maybe useful to specify either your program is probing for services that use UPD or TCP protocol.

Here you go!

 package main

 import (
 "fmt"
 "honnef.co/go/netdb"
 )

 func main() {

 fmt.Println("---------------------------------------")

 var proto *netdb.Protoent
 var serv *netdb.Servent

 // UDP
 proto = netdb.GetProtoByName("udp")

 fmt.Println("List of UDP services with port number : ")
 for portNumber := 25; portNumber <= 80; portNumber++ {

 serv = netdb.GetServByPort(portNumber, proto)

 if serv != nil {
 fmt.Println("Service name : ", serv.Name)
 fmt.Println("Aliases for this service : ")
 for k, v := range serv.Aliases {
 fmt.Println(k, v)
 }
 fmt.Println("Service is using port number : ", serv.Port)
 fmt.Println("######################")
 }

 }

 fmt.Println("---------------------------------------")

 // UDP
 /* proto := netdb.GetProtoByName("udp")
 serv := netdb.GetServByPort(80, proto)

 fmt.Println("Service name : ", serv.Name)
 fmt.Println("Aliases for this service : ")
 for k, v := range serv.Aliases {
 fmt.Println(k, v)
 }
 fmt.Println("Service is using port number : ", serv.Port)

 fmt.Println("---------------------------------------") */

 // TCP
 /* proto2 := netdb.GetProtoByName("tcp")
 serv2 := netdb.GetServByPort(80, proto2)

 fmt.Println("Service name : ", serv2.Name)
 fmt.Println("Aliases for this service : ")
 for k, v := range serv2.Aliases {
 fmt.Println(k, v)
 }
 fmt.Println("Service is using port number : ", serv2.Port) */
 }

Output:

---

List of UDP services with port number :

Service name : smtp

Aliases for this service :

Service is using port number : 25

#

Service name : nsw-fe

Aliases for this service :

Service is using port number : 27

#

Service name : msg-icp

Aliases for this service :

Service is using port number : 29

#

Service name : msg-auth

Aliases for this service :

Service is using port number : 31

#

Service name : dsp

Aliases for this service :

Service is using port number : 33

#

Service name : time

Aliases for this service :

Service is using port number : 37

#

Service name : rap

Aliases for this service :

Service is using port number : 38

#

Service name : rlp

Aliases for this service :

Service is using port number : 39

#

Service name : graphics

Aliases for this service :

Service is using port number : 41

#

.....

References:

http://php.net/manual/en/function.getservbyport.php

https://godoc.org/honnef.co/go/netdb