Skip to main content

Basic Python Server to execute ACME instead of dump clients

Project description

ACME Management Server
======================

[![Build Status](http://img.shields.io/travis/mswart/acme-mgmtserver/master.svg)](https://travis-ci.org/mswart/acme-mgmtserver)


[LetsEncrypt](https://letsencrypt.org) supports issuing free certificates by communication via ACME - the Automatically Certificate Management Evaluation protocol.

This tools is yet another ACME client ... but as a client/server model.


## Why yet another ACME clients

Some aspects are special:

* **Only the server with account information**: It is not that security relevant, but only the ACME Management Server needs access to the account information / key for the ACME server like LetsEncrypt.
* **Only the server requires all the ACME dependencies**: The clients requires only a SSL tool like OpenSSL and a HTTP client like wget or curl, no python, no build tools. Python with python-acme and its dependencies (PyOpenSSL, PyASN.1, ...) is only needed for the server.
* **ACME handling can be put into own VM / container ...**: The server can be placed into a own VM, container, network segment to limit the security risk on compromised systems.
* **Supports distributed web servers**: All `.well-known/acme-challenges` requests from all servers can be served directly by the server. This make it easy to validate domains when using multiple web server in distributed or fail-over fashion.


## Redirect validation requests back to the ACME Management Server.

### Nginx

```
upstream acme-mgmtserver {
server ...;
}
server {
# ...
location /.well-known/acme-challenge {
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_pass http://acme-mgmtserver;
# to support multiple acme mgmt server check challenge on all upstream server:
proxy_next_upstream error timeout http_404;
}
# ...
}
```

This passes all acme challenge to our server. `proxy_next_upstream http_404;` can be used to support multiple ACME management servers and search for the response on all servers.

### Apache

Up to you - I am happy to accept a PR to complete this.


## Installation

My preferred installation is by distribution packages. Due to some new dependencies like `python-acme` and `pyopenssl > 0.15` I use the ACME mgmt-server in a Ubuntu 16.04 LTS xenial container with packages from my own [PPA](https://launchpad.net/~malte.swart/+archive/ubuntu/acme).

But the server and all its dependencies are available on PyPi and can be installed by Python package manager like pip e.g. inside a virtualenv.


## Configuration

The configuration is a basic INI file, with multiple key support. The main parts are a the blocks to define the account direction, listen information for the http interfaces and the configuration which client is allowed to request certificates for which certificates.

```bash
[account]
# the ACME server to talk to; I recommend to first test
# against the staging system
acme-server = https://acme-staging.api.letsencrypt.org/directory
# account dir; contains
# account.pem - private key to identify against the ACME server
# registration.json - the registration resource as JSON dump
dir = /etc/acmems/account/

[listeners]
# listen for HTTP challenge check requests (e.g. from Nginx)
http=192.0.2.80:1380
http=198.51.100.80:1380
http=[fe80::80%eth0]:1380
# Management interface itself, the clients needs to talk to this
mgmt=192.0.2.13:1313
# maximal size for CSR (in bytes)
max-size = 4k

# Define multiple authentification blocks
# a CSR must fulfil all listed authentication methods and must
# only contains listed domains (checks against globs)
[auth "mail"]
# TCP connection must come from one of this IPs
ip=192.0.2.0/24
ip=198.51.100.21
domain=mail.example.org
domain=mail.example.com

# an additional auth block
[auth "ext"]
ip=198.51.100.128/28
domain=*.test.example.org

# CSR must also be signed by HMAC (via a the secret key)
[auth "mail-secure"]
ip=198.51.100.21
hmac_type=sha256
hmac_key=A1YP67armNf3cBrecyJHdb035
domain=mail?.example.org
domain=mail.example.com
```


## Registration

The executable `acme-register` supports to register a the ACME server. This
will not be done automatically, you have to call it manual before the first use of the server itself.

Please call a look at the help output for further instration `acme-register --help`.

A registration could look like this:

```bash
> bin/acme-register --gen-key --register --email test@example.org configs/integration.ini
Generate private key ... done
Initialize ACME client ... done
Register ... done
You need to accept the terms of service at http://127.0.0.1:4001/terms/v1
> bin/acme-register --accept-terms-of-service=http://127.0.0.1:4001/terms/v1 configs/integration.ini
Load private key ... done
Initialize ACME client ... done
Refreshing current registration ... done
You need to accept the terms of service at http://127.0.0.1:4001/terms/v1
Accepting ToS at http://127.0.0.1:4001/terms/v1 ... done
```


## Example Client Usage

```
# generate domain private key (once!)
openssl genrsa 4096 > domain.key

# generate csr to create/renew your certificate
# please generate a new csr for to renew your certificate
openssl req -new -sha256 -key domain.key -subj "/CN=example.org" > domain-201512.csr
# or
openssl req -new -sha256 -key domain.key -subj "/CN=example.org" -reqexts SAN -config <(cat /etc/ssl/openssl.cnf <(printf "[SAN]\nsubjectAltName=DNS:example.org,DNS:www.example.org")) > domain-201512.csr

# upload sign csr with shared key
wget --post-file=domain-201512.csr --header="`openssl dgst -sha256 -hmac '$KEY' domain-201512.csr | sed -e 's/HMAC-\(.*\)(.*)= *\(.*\)/Authentication: hmac name=\L\1\E, hash=\2/'`" http://acmese:1313/sign > domain-201512.pem
# upload csr with out sign
wget --post-file=domain-201512.csr http://acmese:1313/sign > domain-201512.pem
```


## HTTP interface

### Client request

Only POST request to `/sign` are supported.

The body must be a CSR as PEM format; `Content-Length` header is required, `Content-Type` is currently not evaluated.

To authentication the CSR via HMAC, add a header like:

```
Authentication: hmac name=sha256 hash=47d5066525a214c759300d884bdd19d8f461a0ad24a2a0b7b705caee6c912228
```

A complete request could look like:

```
POST /sign HTTP/1.1
Host: 127.0.0.1:4005
Content-Length: 1586
Authentication: hmac name=sha256, hash=47d5066525a214c759300d884bdd19d8f461a0ad24a2a0b7b705caee6c912228

-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----
```


### Server response

Error code:

* **200**: CSR was signed. Response body contains the certificate and the intermediate certification in PEM form.
* **403**: Signing is denied, at a look at your auth blocks / authentication methods; are you missing a `Authentication` header?
* **413**: CSR request is too long. You might increase the `max-size` setting
* **415**: CSR could not be parsed
* **500**: Internal exception - take a look at the log and report the bug


## Testing

The server is mostly tests (some boulder error responses are difficult to reproduce). You need `py.test` to run the tests.

The tests marked as `boulder` needs a local ACME server listening on `127.0.0.1:4000` sends all HTTP01 test challenges to `127.0.0.1:5002`. To install boulder take a look at the [Boulder README](https://github.com/letsencrypt/boulder) and/or at the prepare scripts for travis to setup boulder (`tests/scripts`).


## Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Add tests for your feature.
4. Add your feature.
5. Commit your changes (git commit -am 'Add some feature')
6. Push to the branch (git push origin my-new-feature)
7. Create new Pull Request

## License

GPL License

Copyright (c) 2015, Malte Swart

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

acme-mgmtserver-0.1.1.tar.gz (16.5 kB view hashes)

Uploaded Source

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page