lacme(1)
NAME
lacme - ACME client written with process isolation and minimal privileges in mind
SYNOPSIS
lacme [--config=FILENAME] [--socket=PATH] [OPTION ...] COMMAND [ARGUMENT ...]
DESCRIPTION
lacme is a small ACME client written with process isolation and minimal privileges in mind. It is divided into four components, each with its own executable: 1. A lacme-accountd(1) process to manage the account key and issue SHA-256 signatures needed for each ACME command. (This process binds to a UNIX-domain socket to reply to signature requests from the ACME client.) One can use the UNIX-domain socket forwarding facility of OpenSSH 6.7 and later to run lacme-accountd(1) and lacme on different hosts. Alternatively, the lacme-accountd(1) process can be spawned by the "master" lacme process below; in that case, the two processes communicate through a socket pair. 2. A "master" lacme process, which runs as root and is the only component with access to the private key material of the server keys. It is used to fork the ACME client (and optionally the ACME webserver) after dropping root privileges. For certificate issuances (new-cert command), it also generates Certificate Signing Requests, then verifies the validity of the issued certificate, and optionally reloads or restarts services when the notify option is set. 3. An actual ACME client (specified with the command option of the [client] section of the configuration file), which builds ACME commands and dialogues with the remote ACME server. Since ACME commands need to be signed with the account key, the "master" lacme process passes the lacme-accountd(1) UNIX-domain socket to the ACME client: data signatures are requested by writing the data to be signed to the socket. 4. For certificate issuances (new-cert command), an optional webserver (specified with the command option of the [webserver] section of the configuration file), which is spawned by the "master" lacme process when no service is listening on the HTTP port. (The only challenge type currently supported by lacme is http-01, which requires a webserver to answer challenges.) That webserver only processes GET and HEAD requests under the /.well-known/acme-challenge/ URI. By default some iptables(8) rules are automatically installed to open the HTTP port, and removed afterwards.
COMMANDS
lacme [--agreement-uri=URI] new-reg [CONTACT ...]
Register the account key managed by lacme-accountd(1). A list
of CONTACT information (such as maito: URIs) can be specified in
order for the server to contact the client for issues related to
this registration (such as notifications about server-initiated
revocations).
--agreement-uri= can be used to specify a URI referring to a
subscriber agreement or terms of service provided by the server;
adding this options indicates the client's agreement with the
referenced terms. Note that the server might require the client
to agree to subscriber agreement before performing any further
actions.
If the account key is already registered, lacme prints the URI
of the existing registration and aborts.
lacme [--agreement-uri=URI] reg=URI [CONTACT ...]
Dump or edit the registration URI (relative to the ACME server
URI, which is specified with the server option of the [client]
section of the configuration file).
When specified, the list of CONTACT information and the
agreement URI are sent to the server to replace the existing
values.
lacme [--config-certs=FILE] new-cert [SECTION ...]
Read the certificate configuration FILE (see the certificate
configuration file section below for the configuration options),
and request new Certificate Issuance for each of its sections
(or the given list of SECTIONs).
lacme revoke-cert FILE [FILE ...]
Request that the given certificate(s) FILE(s) be revoked. For
this command, lacme-accountd(1) can be pointed to either the
account key or the server's private key.
GENERIC OPTIONS
--config=filename
Use filename as configuration file. See the configuration file
section below for the configuration options.
--socket=path
Use path as the lacme-accountd(1) UNIX-domain socket to connect
to for signature requests from the ACME client. lacme aborts if
path is readable or writable by other users, or if its parent
directory is writable by other users. This command-line option
overrides the socket option of the [client] section of the
configuration file. Moreover this option is ignored when the
configuration file has an [accountd] section; in that case lacme
spawns lacme-accountd(1), and the two processes communicate
through a socket pair.
-h, --help
Display a brief help and exit.
-q, --quiet
Be quiet.
--debug
Turn on debug mode.
CONFIGURATION FILE
If --config= is not given, lacme uses the first existing configuration
file among ./lacme.conf, $XDG_CONFIG_HOME/lacme/lacme.conf (or
~/.config/lacme/lacme.conf if the XDG_CONFIG_HOME environment variable
is not set), and /etc/lacme/lacme.conf. Valid options are:
DEFAULT SECTION
config-certs
For certificate issuances (new-cert command), specify the
space-separated list of certificate configuration files or
directories to use (see the certificate configuration file
section below for the configuration options).
Paths not starting with / are relative to the directory name of
the configuration filename. The list of files and directories
is processed in order, with the later items taking precedence.
Files in a directory are processed in lexicographic order, only
considering the ones with suffix .conf.
Default: lacme-certs.conf lacme-certs.conf.d/.
[client] SECTION
This section is used for configuring the ACME client (which takes care
of ACME commands and dialogues with the remote ACME server).
socket See --socket=. Default: $XDG_RUNTIME_DIR/S.lacme if the
XDG_RUNTIME_DIR environment variable is set.
user The username to drop privileges to (setting both effective and
real uid). Preserve root privileges if the value is empty (not
recommended). Default: nobody.
group The groupname to drop privileges to (setting both effective and
real gid, and also setting the list of supplementary gids to
that single group). Preserve root privileges if the value is
empty (not recommended). Default: nogroup.
command
Path to the ACME client executable. Default:
/usr/lib/lacme/client.
server Root URI of the ACME server. Default:
https://acme-v01.api.letsencrypt.org/.
timeout
Timeout in seconds after which the client stops polling the ACME
server and considers the request failed. Default: 10.
SSL_verify
Whether to verify the server certificate chain. Default: Yes.
SSL_version
Specify the version of the SSL protocol used to transmit data.
SSL_cipher_list
Specify the cipher list for the connection, see ciphers(1ssl)
for more information.
[webserver] SECTION
This section is used for configuring the ACME webserver.
listen Specify the local address to listen on, in the form
ADDRESS[:PORT]. If ADDRESS is enclosed with brackets `['/']'
then it denotes an IPv6; an empty ADDRESS means 0.0.0.0.
Default: :80.
challenge-directory
If a webserver is already running, specify a non-existent
directory under which the webserver is configured to serve GET
requests for challenge files under /.well-known/acme-challenge/
(for each virtual hosts requiring authorization) as static
files. Default: /var/www/acme-challenge.
user The username to drop privileges to (setting both effective and
real uid). Preserve root privileges if the value is empty (not
recommended). Default: www-data.
group The groupname to drop privileges to (setting both effective and
real gid, and also setting the list of supplementary gids to
that single group). Preserve root privileges if the value is
empty (not recommended). Default: www-data.
command
Path to the ACME webserver executable. Default:
/usr/lib/lacme/webserver.
iptables
Whether to automatically install iptables(8) rules to open the
ADDRESS[:PORT] specified with listen. Theses rules are
automatically removed once lacme exits. Default: Yes.
[accountd] SECTION
This section is used for configuring the lacme-accountd(1) process. If
the section (including its header) is absent or commented out, lacme
connects to an existing UNIX-domain socket bound by a running
lacme-accountd(1) process.
user The username to drop privileges to (setting both effective and
real uid). Preserve root privileges if the value is empty.
group The groupname to drop privileges to (setting both effective and
real gid, and also setting the list of supplementary gids to
that single group). Preserve root privileges if the value is
empty.
command
Path to the lacme-accountd(1) executable. Default:
/usr/bin/lacme-accountd.
config Path to the lacme-accountd(1) configuration file. Default:
/etc/lacme/lacme-accountd.conf.
privkey
The (private) account key to use for signing requests. See
lacme-accountd(1) for details.
quiet Be quiet. Possible values: Yes/No.
CERTIFICATE CONFIGURATION FILE
For certificate issuances (new-cert command), a separate file is used
to configure paths to the certificate and key, as well as the subject,
subjectAltName, etc. to generate Certificate Signing Requests. Each
section denotes a separate certificate issuance. Valid options are:
certificate
Where to store the issued certificate (in PEM format). At least
one of certificate or certificate-chain is required.
certificate-chain
Where to store the issued certificate, concatenated with the
content of the file specified specified with the CAfile option
(in PEM format). At least one of certificate or
certificate-chain is required.
certificate-key
Path the service's private key. This option is required. The
following command can be used to generate a new 4096-bits RSA
key in PEM format with mode 0600:
openssl genrsa 4096 | install -m0600 /dev/stdin /path/to/srv.key
min-days
For an existing certificate, the minimum number of days before
its expiration date the section is considered for re-issuance.
Default: 10.
CAfile Path to the issuer's certificate. This is used for
certificate-chain and to verify the validity of each issued
certificate. Specifying an empty value skip certificate
validation. Default:
/usr/share/lacme/lets-encrypt-x3-cross-signed.pem.
hash Message digest algorithm to sign the Certificate Signing Request
with.
keyUsage
Comma-separated list of Key Usages, see x509v3_config(5ssl).
subject
Subject field of the Certificate Signing Request, in the form
/type0=value0/type1=value1/type2=.... This option is required.
subjectAltName
Comma-separated list of Subject Alternative Names, in the form
type0:value1,type1:value1,type2:... The only type currently
supported is DNS, to specify an alternative domain name.
chown An optional username[:groupname] to chown the issued certificate
and certificate-chain to.
chmod An optional octal mode to chmod the issued certificate and
certificate-chain to.
notify Command to pass the the system's command shell (/bin/sh -c)
after successful installation of the certificate and/or
certificate-chain.
EXAMPLES
~$ sudo lacme new-reg mailto:noreply@example.com
~$ sudo lacme reg=/acme/reg/123456 --agreement-uri=https://letsencrypt.org/documents/LE-SA-v1.1.1-August-1-2016.pdf
~$ sudo lacme new-cert
~$ sudo lacme revoke-cert /path/to/server/certificate.pem
BUGS AND FEEDBACK
Bugs or feature requests for lacme should be filed with the Debian project's bug tracker at <https://www.debian.org/Bugs/>.
SEE ALSO
lacme-accountd(1)
AUTHORS
Guilhem Moulin (mailto:guilhem@fripost.org).
December 2015 lacme(1)
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