NAME
acme-client
—
ACME client
SYNOPSIS
acme-client |
[-ADFnrv ] [-f
configfile] domain |
DESCRIPTION
acme-client
is an Automatic Certificate
Management Environment (ACME) client: it looks in its configuration for a
domain section corresponding to the domain given as
command line argument and uses that configuration to retrieve an X.509
certificate which can be used to provide domain name validation (i.e. prove
that the domain is who it says it is). The certificates are typically used
to provide HTTPS for web servers, but can be used in any situation where
domain name validation is required (such as mail servers).
Before a certificate can be requested, an account key needs to be
created using the -A
argument. The first time a
certificate is requested, a domain key needs to be created with
-D
. So a typical invocation the first time it's run
would be:
# acme-client -ADv
example.com
If the certificate already exists and is less than 30 days from
expiry, acme-client
attempts to renew the
certificate.
In order to prove that the client has access to the domain, a
challenge is issued by the signing authority.
acme-client
implements the “http-01”
challenge type, where a file is created within a directory accessible by a
locally run web server. The default challenge directory
/var/www/acme can be served by
httpd(8) with this location block, which will properly map response
challenges:
location "/.well-known/acme-challenge/*" { root "/acme" request strip 2 }
The options are as follows:
-A
- Create a new RSA account key if one does not already exist.
-D
- Create a new RSA domain key if one does not already exist.
-F
- Force certificate renewal, even if it's too soon.
-f
configfile- Specify an alternative configuration file.
-n
- No operation: check and print configuration.
-r
- Revoke the X.509 certificate.
-v
- Verbose operation. Specify twice to also trace communication and data transfers.
- domain
- The domain name.
FILES
- /etc/acme
- Private keys for
acme-client
. - /etc/acme-client.conf
- Default configuration.
- /var/www/acme
- Default challengedir.
EXIT STATUS
acme-client
returns 0 if certificates were
changed (revoked or updated), 1 on failure, or 2 if the certificates didn't
change (up to date).
EXAMPLES
Example configuration files for
acme-client
and
httpd(8) are provided in
/etc/examples/acme-client.conf and
/etc/examples/httpd.conf.
To generate a certificate for example.com and use it to provide HTTPS, create acme-client.conf and httpd.conf and run:
# acme-client -ADv example.com
&& rcctl reload httpd
A cron(8) job can renew the certificate as necessary. On renewal, httpd(8) is reloaded:
0 * * * * sleep $((RANDOM \% 2048)) && \ acme-client example.com && rcctl reload httpd
SEE ALSO
STANDARDS
Automatic Certificate Management Environment (ACME), https://tools.ietf.org/html/draft-ietf-acme-acme-03.
HISTORY
The acme-client
utility first appeared in
OpenBSD 6.1.
AUTHORS
The acme-client
utility was written by
Kristaps Dzonsons
<kristaps@bsd.lv>.
BUGS
The challenge and certificate processes currently retain their (root) privileges.
For the time being, acme-client
only
supports RSA as an account key format.