Welcome to certbot-dns-rfc2136’s documentation!¶
The dns_rfc2136
plugin automates the process of
completing a dns-01
challenge (DNS01
) by creating, and
subsequently removing, TXT records using RFC 2136 Dynamic Updates.
Named Arguments¶
--dns-rfc2136-credentials |
RFC 2136 credentials INI file. (Required) |
--dns-rfc2136-propagation-seconds |
The number of seconds to wait for DNS to propagate before asking the ACME server to verify the DNS record. (Default: 60) |
Credentials¶
Use of this plugin requires a configuration file containing the target DNS server and optional port that supports RFC 2136 Dynamic Updates, the name of the TSIG key, the TSIG key secret itself and the algorithm used if it’s different to HMAC-MD5.
# Target DNS server
dns_rfc2136_server = 192.0.2.1
# Target DNS port
dns_rfc2136_port = 53
# TSIG key name
dns_rfc2136_name = keyname.
# TSIG key secret
dns_rfc2136_secret = 4q4wM/2I180UXoMyN4INVhJNi8V9BCV+jMw2mXgZw/CSuxUT8C7NKKFs AmKd7ak51vWKgSl12ib86oQRPkpDjg==
# TSIG key algorithm
dns_rfc2136_algorithm = HMAC-SHA512
The path to this file can be provided interactively or using the
--dns-rfc2136-credentials
command-line argument. Certbot records the
path to this file for use during renewal, but does not store the file’s contents.
Caution
You should protect this TSIG key material as it can be used to potentially
add, update, or delete any record in the target DNS server. Users who can
read this file can use these credentials to issue arbitrary API calls on
your behalf. Users who can cause Certbot to run using these credentials can
complete a dns-01
challenge to acquire new certificates or revoke
existing certificates for associated domains, even if those domains aren’t
being managed by this server.
Certbot will emit a warning if it detects that the credentials file can be
accessed by other users on your system. The warning reads “Unsafe permissions
on credentials configuration file”, followed by the path to the credentials
file. This warning will be emitted each time Certbot uses the credentials file,
including for renewal, and cannot be silenced except by addressing the issue
(e.g., by using a command like chmod 600
to restrict access to the file).
Sample BIND configuration¶
Here’s a sample BIND configuration for Certbot to use. You will need to generate a new TSIG key, include it in the BIND configuration and grant it permission to issue updates on the target DNS zone.
dnssec-keygen -a HMAC-SHA512 -b 512 -n HOST keyname.
Note
There are a few tools shipped with BIND that can all generate TSIG keys;
dnssec-keygen
, rndc-confgen
, and ddns-confgen
. Try and use the
most secure algorithm supported by your DNS server.
key "keyname." {
algorithm hmac-sha512;
secret "4q4wM/2I180UXoMyN4INVhJNi8V9BCV+jMw2mXgZw/CSuxUT8C7NKKFs AmKd7ak51vWKgSl12ib86oQRPkpDjg==";
};
zone "example.com." IN {
type master;
file "named.example.com";
update-policy {
grant keyname. name _acme-challenge.example.com. txt;
};
};
Note
This configuration limits the scope of the TSIG key to just be able to
add and remove TXT records for one specific host for the purpose of
completing the dns-01
challenge. If your version of BIND doesn’t
support the
update-policy
directive then you can use the less-secure
allow-update
directive instead.
Examples¶
certbot certonly \
--dns-rfc2136 \
--dns-rfc2136-credentials ~/.secrets/certbot/rfc2136.ini \
-d example.com
certbot certonly \
--dns-rfc2136 \
--dns-rfc2136-credentials ~/.secrets/certbot/rfc2136.ini \
-d example.com \
-d www.example.com
certbot certonly \
--dns-rfc2136 \
--dns-rfc2136-credentials ~/.secrets/certbot/rfc2136.ini \
--dns-rfc2136-propagation-seconds 30 \
-d example.com