Book Image

Security with Go

By : John Daniel Leon
Book Image

Security with Go

By: John Daniel Leon

Overview of this book

Go is becoming more and more popular as a language for security experts. Its wide use in server and cloud environments, its speed and ease of use, and its evident capabilities for data analysis, have made it a prime choice for developers who need to think about security. Security with Go is the first Golang security book, and it is useful for both blue team and red team applications. With this book, you will learn how to write secure software, monitor your systems, secure your data, attack systems, and extract information. Defensive topics include cryptography, forensics, packet capturing, and building secure web applications. Offensive topics include brute force, port scanning, packet injection, web scraping, social engineering, and post exploitation techniques.
Table of Contents (15 chapters)

Finding named hosts on a network

If you have just gained access to a network, one of the first things you can do is to get an idea of what hosts are on the network. You can scan all IP addresses on a subnet and then do a DNS lookup to see if you can find any named hosts. Hostnames can have descriptive or informative names that give clues as to what a server may be running.

The pure Go resolver is default and can only block a goroutine instead of a system thread, making it a little more efficient. You can explicitly set the DNS resolver with an environment variable:

export GODEBUG=netdns=go    # Use pure Go resolver (default)
export GODEBUG=netdns=cgo # Use cgo resolver

This example looks for every possible host on a subnet and tries to resolve a hostname for each IP:

package main

import (

var subnetToScan...