acme.sh VS acme-dns-server

A self-signed certificate was generated and used by Proxmox which will always generate a warning on the browser. I did not like seeing this when trying to work on my home lab. So, I started looking for ways to put a valid SSL certificate in Proxmox. During my research, I found that Proxmox could be made to integrate with acme.sh; a free SSL certificate generator powered by ACME(Let's Encrypt).

Next, we will install acme.sh, a command-line tool for managing SSL/TLS certificates. I prefer acme.sh over certbot, as it does not depend on the OS version. For more details about acme.sh, check its GitHub repo here.

A very relevant question. Acme.sh, a similar shell script ACME client, had a remote code execution problem last year.

https://github.com/acmesh-official/acme.sh/issues/4668

As a result, any certificates issued (or renewed) after Feb 8th will not work on older Android devices (< 7.1.1), unless the ACME client has been configure to request an alternate certificate chain. The "alternate chain" workaround will also stop working on June 6th.

I need to support these older Android devices so I am looking for alternatives. I have seen ZeroSSL mentioned a few times; it is also the default CA for acme.sh (the ACME client I am using nowadays) [2]. They have a number of paid plans but ACME certificates are free [3].

I'll be testing this over the next few days, but I would also like to ask if people here have experience with ZeroSSL (good or bad :-). Any feedback would be helpful.

[1]: https://letsencrypt.org/2023/07/10/cross-sign-expiration.html

[2]: https://github.com/acmesh-official/acme.sh

[3]: https://zerossl.com/documentation/acme/

Huh, the environment variable thing was specifically aimed at acme.sh which rather arbitrarily changed the config value from ACMEDNS_UPDATE_URL to ACMEDNS_BASE_URL, never acknowledged this in a changelog and then silently failed after an automatic upgrade as recommended by the default install:

https://github.com/acmesh-official/acme.sh/commit/2ce145f359...

It's also cleared out my .account.conf files when run on the suggested cron.

I've started using updown which also monitors my TLS certs simply because I no longer trust the process to work as documented.

It depends on your provider though. I can tell from experience that with OVH and their API, it's been easy to set up the automatic renewal via DNS verification. Apparently, the official client has support for the DNS API of 159 providers: https://github.com/acmesh-official/acme.sh/wiki/dnsapi

For the few people here that happen to run a self-hosted email server with acme.sh for TLS key/cert generation and Cloudflare for DNS management, I have made a tool that i personally use to get a perfect 100% score on Internet.nl's email test.

All of this is to say it's a decent amount of work to save the hassle of deploying certbot or acme.sh on the remote machines, pick your poison.

Here is a really solid guide for setting up the ACME DNS challenge with pretty much any DNS provider

People wonder why I like using the shell-based ACME client like dehydrated (or acme.sh):

* https://packages.debian.org/search?keywords=dehydrated

* https://github.com/acmesh-official/acme.sh

Versus the official client certbot:

* https://packages.debian.org/search?keywords=python3-certbot

A kludgy as very long shell scripts are (thought to be), I have a better chance of being able to go through all the code and understand it than a dozen(+) Python libraries.

DNS alias mode:

* https://dan.langille.org/2019/02/01/acme-domain-alias-mode/

* https://github.com/acmesh-official/acme.sh/wiki/DNS-alias-mo...

* https://www.eff.org/deeplinks/2018/02/technical-deep-dive-se...

You want the name "internal.example.com". In your external DNS you create a CNAME from "_acme-challenge.internal.example.com" and point it to (e.g.) "internal.example.net" or "internal.dns-auth.example.com"

When you request the certificate you specify the "dns-01" method. The issuer (e.g., LE) will go to the the external DNS server for the look up, see that it is a CNAME and then follow the CNAME/alias, and do the verification at the final hostname.

So your ACME client has to do a DNS (TXT) record update, which can often be done via various APIs, e.g.:

* https://github.com/AnalogJ/lexicon

You can even run your own DNS server locally (in a DMZ?) if your DNS provider does not have an convenient API. There are servers written for this use case:

* https://github.com/joohoi/acme-dns

* https://github.com/joohoi/acme-dns-certbot-joohoi

* https://github.com/pawitp/acme-dns-server

I already had Bind on the machine so it was logical to add the zone there and utilize nsupdate : https://gist.github.com/kronthto/893715f12cc0b1cda9fcfdbd8dc...

But what you are suggesting should work just fine aswell - there should be no need for a persistent service. Of course the service would need to run on port 53, so you actually cannot have another nameserver on that machine already, and also require CAP_NET_BIND_SERVICE .

A quick search lead me to this python project that could be an inspiration: https://github.com/pawitp/acme-dns-server