certchecker

Summary

Certificate checker is a command-line application written in Go that can perform an ad-hoc check to web servers. This check will return basic information about the web servers certificate. More importanly, if it's expired. For now this is the beginning stage of the application. But, the overall vision is to have an app that will iterate through a list of servers and provide this data in various reporting formats. Such as email, pdf, txt, csv, etc.

This can be accomplished with Nagios or OpenSSL. But, this is intended for use outside of standard monitoring platforms or just to provide output that's simple. Plus, it's been a desired project of mine for learning Go and to see where Go can be used.

Roadmap

At the moment this application provides simple information back about the expiry of a TLS certificate. But, down the road I intend on the following. Just some next steps until the next release tag.

1. Pulling more data from the certificate for the site.
2. Using a configuration file to have a daemonized process that will pull this data from multiple sites.
3. Reports sent via email, sms, or chat integrations.
4. The ability to separate entities and report to them with data that only concerns their infrastructure.
5. Potential sponsorship to manage it in various package repositories of different Linux distros.
6. Ability to send the data concerning a TLS certificate to a database.

This is just a simple writeup for next steps related to this project. Please let me know if anyone wants features not listed above.

Build

The current build will be undergoing a refactoring at some point.

Latest Stable Build: v1.0.0

Build process is to build it and move it to the /usr/local/bin. Which seems to work on the Linux systems I've tested.

I have not tested this on Mac or Windows. Upon testing, I will have more results.

Build the application.

go build

Move it to the /usr/local/bin directory or any other path you desire.

sudo mv ./certchecker /usr/local/bin

Usage

Applciation can be run by issuing the command with a target host. Not URL. The application will take care of the url portion for you for now.

help

Here is the help to provide an overview of the usage for this applciation.

Check that TLS certificates are valid.

Usage:
  certchecker [flags]
  certchecker [command]

Available Commands:
  completion  Generate the autocompletion script for the specified shell
  help        Help about any command
  version     Print version for certchecker

Flags:
  -h, --help            help for certchecker
  -s, --server string   hostname for site being tested (i.g. www.n3s0.tech)

Use "certchecker [command] --help" for more information about a command.

Example

Below is an example of how it can be used and what information it can provide.

certchecker -s www.n3s0.tech

The output for this command can be found below.

|---------------------------------------|
|-- Certificate Checker (certchecker) --|
|---------------------------------------|
╭─ Server: www.n3s0.tech
│  ├─ TLS Version: TLS 1.3
│  ├─ Cipher Suite: TLS_AES_128_GCM_SHA256
│  ╰─ Subject: CN=www.n3s0.tech
├─ Certificate Dates:
│  ├─ Not Before: Sun, 17 Nov 2024 19:44:48 CST
│  ╰─ Not After: Sat, 15 Feb 2025 19:44:47 CST
│     ╰─ Status: Valid
╰─ Client Information:
   ╰─ Local Date/Time: Sun, 15 Dec 2024 03:36:48 CST

Another option available is to issue this for a specific port. Which can be useful when the standard HTTPS port isn't being used.

certcecker -s example.com -p 65443