unbound-anchor - Unbound 1.24.0 anchor utility.
unbound-anchor performs setup or update of the root trust
anchor for DNSSEC validation. The program fetches the trust anchor with the
method from RFC 7958 when regular RFC 5011 update fails to
bring it up to date. It can be run (as root) from the commandline, or run as
part of startup scripts. Before you start the unbound(8) DNS
server.
Suggested usage:
# in the init scripts.
# provide or update the root anchor (if necessary)
unbound-anchor -a "/var/unbound/db/root.key"
# Please note usage of this root anchor is at your own risk
# and under the terms of our LICENSE (see source).
#
# start validating resolver
# the unbound.conf contains:
# auto-trust-anchor-file: "/var/unbound/db/root.key"
unbound -c unbound.conf
This tool provides builtin default contents for the root anchor
and root update certificate files.
It tests if the root anchor file works, and if not, and an update
is possible, attempts to update the root anchor using the root update
certificate. It performs a https fetch of root-anchors.xml and checks
the results (RFC 7958); if all checks are successful, it updates the
root anchor file. Otherwise the root anchor file is unchanged. It performs
RFC 5011 tracking if the DNSSEC information available via the DNS
makes that possible.
It does not perform an update if the certificate is expired, if
the network is down or other errors occur.
The available options are:
- -a <file>
- The root anchor key file, that is read in and written out. Default is
/var/unbound/db/root.key. If the file does not exist, or is empty,
a builtin root key is written to it.
- -c <file>
- The root update certificate file, that is read in. Default is
/var/unbound/etc/icannbundle.pem. If the file does not exist, or is
empty, a builtin certificate is used.
- -l
- List the builtin root key and builtin root update certificate on
stdout.
- -u <name>
- The server name, it connects to https://name. Specify without
https:// prefix. The default is "data.iana.org".
It connects to the port specified with -P. You can pass an IPv4
address or IPv6 address (no brackets) if you want.
- -S
- Do not use SNI for the HTTPS connection. Default is to use SNI.
- -b <address>
- The source address to bind to for domain resolution and contacting the
server on https. May be either an IPv4 address or IPv6 address (no
brackets).
- -x <path>
- The pathname to the root-anchors.xml file on the server. (forms URL with
-u). The default is /root-anchors/root-anchors.xml.
- -s <path>
- The pathname to the root-anchors.p7s file on the server. (forms URL with
-u). The default is /root-anchors/root-anchors.p7s. This
file has to be a PKCS7 signature over the xml file, using the pem file
(-c) as trust anchor.
- -n <name>
- The emailAddress for the Subject of the signer's certificate from the p7s
signature file. Only signatures from this name are allowed. The default is
dnssec@iana.org. If you pass "" then the
emailAddress is not checked.
- -4
- Use IPv4 for domain resolution and contacting the server on https. Default
is to use IPv4 and IPv6 where appropriate.
- -6
- Use IPv6 for domain resolution and contacting the server on https. Default
is to use IPv4 and IPv6 where appropriate.
- -f
<resolv.conf>
- Use the given resolv.conf file. Not enabled by default, but you could try
to pass /etc/resolv.conf on some systems. It contains the IP
addresses of the recursive nameservers to use. However, since this tool
could be used to bootstrap that very recursive nameserver, it would not be
useful (since that server is not up yet, since we are bootstrapping it).
It could be useful in a situation where you know an upstream cache is
deployed (and running) and in captive portal situations.
- -r
<root.hints>
- Use the given root.hints file (same syntax as the BIND and Unbound root
hints file) to bootstrap domain resolution. By default a list of builtin
root hints is used. unbound-anchor goes to the network itself for these
roots, to resolve the server (-u option) and to check the root
DNSKEY records. It does so, because the tool when used for bootstrapping
the recursive resolver, cannot use that recursive resolver itself because
it is bootstrapping that server.
- -R
- Allow fallback from -f <resolv.conf> file to direct
root servers query. It allows you to prefer local resolvers, but fallback
automatically to direct root query if they do not respond or do not
support DNSSEC.
- -v
- More verbose. Once prints informational messages, multiple times may
enable large debug amounts (such as full certificates or byte-dumps of
downloaded files). By default it prints almost nothing. It also prints
nothing on errors by default; in that case the original root anchor file
is simply left undisturbed, so that a recursive server can start right
after it.
- -C
<unbound.conf>
- Debug option to read <unbound.conf> into the resolver process
used.
- -P <port>
- Set the port number to use for the https connection. The default is
443.
- -F
- Debug option to force update of the root anchor through downloading the
xml file and verifying it with the certificate. By default it first tries
to update by contacting the DNS, which uses much less bandwidth, is much
faster (200 msec not 2 sec), and is nicer to the deployed infrastructure.
With this option, it still attempts to do so (and may verbosely tell you),
but then ignores the result and goes on to use the xml fallback
method.
- -h
- Show the version and commandline option help.
This tool exits with value 1 if the root anchor was updated using
the certificate or if the builtin root-anchor was used. It exits with code 0
if no update was necessary, if the update was possible with RFC 5011
tracking, or if an error occurred.
You can check the exit value in this manner:
unbound-anchor -a "root.key" || logger "Please check root.key"
Or something more suitable for your operational environment.
The root keys and update certificate included in this tool are
provided for convenience and under the terms of our license (see the LICENSE
file in the source distribution or
https://github.com/NLnetLabs/unbound/blob/master/LICENSE and might be
stale or not suitable to your purpose.
By running unbound-anchor -l the keys and certificate that
are configured in the code are printed for your convenience.
The built-in configuration can be overridden by providing a
root-cert file and a rootkey file.
- /var/unbound/db/root.key
- The root anchor file, updated with 5011 tracking, and read and written to.
The file is created if it does not exist.
- /var/unbound/etc/icannbundle.pem
- The trusted self-signed certificate that is used to verify the downloaded
DNSSEC root trust anchor. You can update it by fetching it from
https://data.iana.org/root-anchors/icannbundle.pem (and validate
it). If the file does not exist or is empty, a builtin version is
used.
- https://data.iana.org/root-anchors/root-anchors.xml
- Source for the root key information.
- https://data.iana.org/root-anchors/root-anchors.p7s
- Signature on the root key information.
unbound.conf(5), unbound(8).
Unbound developers are mentioned in the CREDITS file in the
distribution.