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https://github.com/yaroslaff/showcert
Simple OpenSSL for humans: all you need for X.509 TLS certificates (and nothing more).
https://github.com/yaroslaff/showcert
cert certificate certificates cli crt expiration expiration-control generate https inspect letsencrypt network openssl pem python python3 shell ssl tls x509
Last synced: 3 days ago
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Simple OpenSSL for humans: all you need for X.509 TLS certificates (and nothing more).
- Host: GitHub
- URL: https://github.com/yaroslaff/showcert
- Owner: yaroslaff
- License: mit
- Created: 2022-06-12T06:53:52.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2024-12-23T18:31:48.000Z (29 days ago)
- Last Synced: 2025-01-11T23:10:29.027Z (10 days ago)
- Topics: cert, certificate, certificates, cli, crt, expiration, expiration-control, generate, https, inspect, letsencrypt, network, openssl, pem, python, python3, shell, ssl, tls, x509
- Language: Python
- Homepage:
- Size: 85.9 KB
- Stars: 87
- Watchers: 4
- Forks: 5
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# showcert - simple OpenSSL for humans
showcert consist of two CLI utilities: `showcert` itself - all 'read' operations with X.509 certificates and `gencert` - to create certificates for development purposes.
showcert tries to follow these principles:
- Simple things must be simple. More complex things may require some options.
- Be simple and cover 9/10 routine certificate-related tasks.
- If showcert missing some rarely used feature and user needs to use openssl for it - okay.
## showcert
micro-cheatsheet (only 5 most often used commands):
~~~bash
# Remote:
showcert github.com
showcert smtp.google.com:25
# save remote certificate or whole --chain
showcert --chain -o pem google.com > google-fullchain.pem
# Local:
# -i for insecure (process self-signed or expired certificates)
showcert -i /etc/ssl/certs/ssl-cert-snakeoil.pem
# letsencrypt-special sugar
sudo showcert -q :le -w50 || echo local LetsEncrypt certificates will expire in less then 50 days
~~~
~~~bash
# You will never forget how to use it:
$ showcert github.com
IP: 140.82.121.3
Names: github.com www.github.com
notBefore: 2022-03-15 00:00:00 (182 days old)
notAfter: 2023-03-15 23:59:59 (183 days left)
Issuer: C=US O=DigiCert Inc CN=DigiCert TLS Hybrid ECC SHA384 2020 CA1
# Compare it against openssl:
# two redirections, pipe, two invocations and 5 unneeded options
$ openssl s_client -connect github.com:443 /dev/null | openssl x509 -inform pem -text
# View Google SMTP server cert. starttls mode selected automatically. Same for POP3/IMAP and any simple TLS service
$ showcert smtp.google.com:25
# Save full chain of google.com certificates to local PEM file
$ showcert --chain -o pem google.com > google-fullchain.pem
# Warn about any LetsEncrypt cert which will expire in 50 days or less
# :le is just special token, replaced to /etc/letsencrypt/live/*/fullchain.pem
$ sudo showcert -q :le -w50 || echo panic
/etc/letsencrypt/live/my.example.com/fullchain.pem expires in 47 days
panic
~~~
### STARTTLS implementation
showcert has built-in support for STARTTLS for SMTP (port 25), POP3 (port 110) and IMAP (port 143). You can select proper method with `--starttls` option (or disable it with `--starttls no`), but default value (`auto`) is OK for most cases. This option is needed only if you test servers on non-standard ports.
### Exit code
showcert will return non-zero exit code (1) in case of any error (including expired certificate or host mismatch).
If `-w DAYS` used, non-zero (2) will be returned for valid certificates, which will expire in `DAYS` days or sooner.
### Usage
~~~shell
$ bin/showcert -h
usage: showcert [-h] [-i] [--output OUTPUT] [-c] [-w [DAYS]] [-q] [-n NAME] [-t METHOD] [-l TIME]
[--ca CA] [--net]
CERT [CERT ...]
Show local/remote SSL certificate info v0.1.15
positional arguments:
CERT path, - (stdin), ":le" (letsencrypt cert path), hostname or hostname:port
optional arguments:
-h, --help show this help message and exit
-i, --insecure Do not verify remote certificate
--output OUTPUT, -o OUTPUT
output format: brief, full, names, dnames (for certbot), pem, no.
-c, --chain Show chain (not only server certificate)
-w [DAYS], --warn [DAYS]
Warn about expiring certificates (def: 20 days)
Rarely needed options:
-q, --quiet Quiet mode, same as --output no
-n NAME, --name NAME name for SNI (if not same as CERT host)
-t METHOD, --starttls METHOD
starttls method: auto (default, and OK almost always), no, imap, smtp, pop3
-l TIME, --limit TIME
socket timeout (def: 5)
--ca CA path to trusted CA certificates, def: /usr/local/lib/python3.9/dist-packages/certifi/cacert.pem
--net Force network check (if you want to check host and have file/dir with same name in current directory)
Examples:
# just check remote certificate
bin/showcert example.com
# check SMTP server certificate (autodetected: --starttls smtp )
bin/showcert smtp.google.com:25
# save fullchain from google SMTP to local PEM file
bin/showcert --chain -o pem google.com > google-fullchain.pem
# look for expiring letsencrypt certificates
# :le is alias for /etc/letsencrypt/live/*/fullchain.pem
bin/showcert :le -q -w 20 || echo "expiring soon!"
~~~
## gencert
Gencert is simple tool to quickly generate X.509 certificates **for development purposes**.
I am not sure if they are very secure. Do not use it in real production!
### Generate self-signed cert
~~~shell
gencert example.com www.example.com
~~~
This will make `example.com.pem` file with both certificate and key in one file. Add `--key example.com.key` to store key in separate file. Add `--cert mycert.pem` to store certificate in different file name.
### Your own CA in two simple commands
Generate CA cert/key:
~~~shell
gencert --ca "My own CA"
~~~
This will make My-own-CA.pem and private key My-own-CA.key (Override with `--cert` and `--key`).
Generate signed certificate:
~~~shell
gencert --cacert My-own-CA.pem example.com
~~~
Done!
`--cacert` is required, `--cakey` is optional (omitted in example), gencert will look for CA private key in following order:
- in`--cakey` PEM file (if given)
- in `--cacert` PEM file (if will be found there).
- guessed filename. If `--cacert` is CA.pem, gencert will try to load from CA.key.
You may verify certificate with showcert and openssl:
~~~shell
# verify with showcert (unless '-i' given, showcert expects a valid certificate)
$ showcert --ca MyCA.pem example.com.pem
Names: example.com
notBefore: 2024-01-26 11:30:24 (0 days old)
notAfter: 2025-01-25 11:30:24 (364 days left)
Issuer: CN=MyCA
# verify with openssl
$ openssl verify -CAfile MyCA.pem example.com.pem
example.com.pem: OK
~~~
## Installation
`pipx install showcert`
Or right from repo: `pipx install git+https://github.com/yaroslaff/showcert`
Or use old way via pip/pip3:
- `pip3 install showcert` (just install)
- `pip3 install -U showcert` (upgrade)
- `pip3 install -U git+https://github.com/yaroslaff/showcert` (install/upgrade from git)