resolvectl

RESOLVECTL(1) resolvectl RESOLVECTL(1)

NAME
resolvectl, resolvconf, systemd-resolve - Resolve domain names, IPV4
and IPv6 addresses, DNS resource records, and services; introspect and
reconfigure the DNS resolver

SYNOPSIS
resolvectl [OPTIONS...] {COMMAND} [NAME...]

DESCRIPTION
resolvectl may be used to resolve domain names, IPv4 and IPv6
addresses, DNS resource records and services with the systemd-
resolved.service(8) resolver service. By default, the specified list of
parameters will be resolved as hostnames, retrieving their IPv4 and
IPv6 addresses. If the parameters specified are formatted as IPv4 or
IPv6 operation the reverse operation is done, and a hostname is
retrieved for the specified addresses.

The program's output contains information about the protocol used for
the look-up and on which network interface the data was discovered. It
also contains information on whether the information could be
authenticated. All data for which local DNSSEC validation succeeds is
considered authenticated. Moreover all data originating from local,
trusted sources is also reported authenticated, including resolution of
the local host name, the "localhost" host name or all data from
/etc/hosts.

COMMANDS
query HOSTNAME|ADDRESS...
Resolve domain names, IPv4 and IPv6 addresses.

service [[NAME] TYPE] DOMAIN
Resolve DNS-SD[1] and SRV[2] services, depending on the specified
list of parameters. If three parameters are passed the first is
assumed to be the DNS-SD service name, the second the SRV service
type, and the third the domain to search in. In this case a full
DNS-SD style SRV and TXT lookup is executed. If only two parameters
are specified, the first is assumed to be the SRV service type, and
the second the domain to look in. In this case no TXT RR is
requested. Finally, if only one parameter is specified, it is
assumed to be a domain name, that is already prefixed with an SRV
type, and an SRV lookup is done (no TXT).

openpgp EMAIL@DOMAIN...
Query PGP keys stored as OPENPGPKEY[3] resource records. Specified
e-mail addresses are converted to the corresponding DNS domain
name, and any OPENPGPKEY keys are printed.

tlsa [FAMILY] DOMAIN[:PORT]...
Query TLS public keys stored as TLSA[4] resource records. A query
will be performed for each of the specified names prefixed with the
port and family ("_port._family.domain"). The port number may be
specified after a colon (":"), otherwise 443 will be used by
default. The family may be specified as the first argument,
otherwise tcp will be used.

status [LINK...]
Shows the global and per-link DNS settings currently in effect. If
no command is specified, this is the implied default.

statistics
Shows general resolver statistics, including information whether
DNSSEC is enabled and available, as well as resolution and
validation statistics.

reset-statistics
Resets the statistics counters shown in statistics to zero. This
operation requires root privileges.

flush-caches
Flushes all DNS resource record caches the service maintains
locally. This is mostly equivalent to sending the SIGUSR2 to the
systemd-resolved service.

reset-server-features
Flushes all feature level information the resolver learnt about
specific servers, and ensures that the server feature probing logic
is started from the beginning with the next look-up request. This
is mostly equivalent to sending the SIGRTMIN+1 to the
systemd-resolved service.

dns [LINK [SERVER...]], domain [LINK [DOMAIN...]], default-route [LINK
[BOOL...]], llmnr [LINK [MODE]], mdns [LINK [MODE]], dnssec [LINK
[MODE]], dnsovertls [LINK [MODE]], nta [LINK [DOMAIN...]]
Get/set per-interface DNS configuration. These commands may be used
to configure various DNS settings for network interfaces. These
commands may be used to inform systemd-resolved or systemd-networkd
about per-interface DNS configuration determined through external
means. The dns command expects IPv4 or IPv6 address specifications
of DNS servers to use. The domain command expects valid DNS
domains, possibly prefixed with "~", and configures a per-interface
search or route-only domain. The default-route command expects a
boolean parameter, and configures whether the link may be used as
default route for DNS lookups, i.e. if it is suitable for lookups
on domains no other link explicitly is configured for. The llmnr,
mdns, dnssec and dnsovertls commands may be used to configure the
per-interface LLMNR, MulticastDNS, DNSSEC and DNSOverTLS settings.
Finally, nta command may be used to configure additional
per-interface DNSSEC NTA domains.

Commands dns, domain and nta can take a single empty string
argument to clear their respective value lists.

For details about these settings, their possible values and their
effect, see the corresponding settings in systemd.network(5).

revert LINK
Revert the per-interface DNS configuration. If the DNS
configuration is reverted all per-interface DNS setting are reset
to their defaults, undoing all effects of dns, domain,
default-route, llmnr, mdns, dnssec, dnsovertls, nta. Note that when
a network interface disappears all configuration is lost
automatically, an explicit reverting is not necessary in that case.

OPTIONS
-4, -6
By default, when resolving a hostname, both IPv4 and IPv6 addresses
are acquired. By specifying -4 only IPv4 addresses are requested,
by specifying -6 only IPv6 addresses are requested.

-i INTERFACE, --interface=INTERFACE
Specifies the network interface to execute the query on. This may
either be specified as numeric interface index or as network
interface string (e.g. "en0"). Note that this option has no effect
if system-wide DNS configuration (as configured in /etc/resolv.conf
or /etc/systemd/resolve.conf) in place of per-link configuration is
used.

-p PROTOCOL, --protocol=PROTOCOL
Specifies the network protocol for the query. May be one of "dns"
(i.e. classic unicast DNS), "llmnr" (Link-Local Multicast Name
Resolution[5]), "llmnr-ipv4", "llmnr-ipv6" (LLMNR via the indicated
underlying IP protocols), "mdns" (Multicast DNS[6]), "mdns-ipv4",
"mdns-ipv6" (MDNS via the indicated underlying IP protocols). By
default the lookup is done via all protocols suitable for the
lookup. If used, limits the set of protocols that may be used. Use
this option multiple times to enable resolving via multiple
protocols at the same time. The setting "llmnr" is identical to
specifying this switch once with "llmnr-ipv4" and once via
"llmnr-ipv6". Note that this option does not force the service to
resolve the operation with the specified protocol, as that might
require a suitable network interface and configuration. The special
value "help" may be used to list known values.

-t TYPE, --type=TYPE, -c CLASS, --class=CLASS
Specifies the DNS resource record type (e.g. A, AAAA, MX, ...) and
class (e.g. IN, ANY, ...) to look up. If these options are used a
DNS resource record set matching the specified class and type is
requested. The class defaults to IN if only a type is specified.
The special value "help" may be used to list known values.

--service-address=BOOL
Takes a boolean parameter. If true (the default), when doing a
service lookup with --service the hostnames contained in the SRV
resource records are resolved as well.

--service-txt=BOOL
Takes a boolean parameter. If true (the default), when doing a
DNS-SD service lookup with --service the TXT service metadata
record is resolved as well.

--cname=BOOL
Takes a boolean parameter. If true (the default), DNS CNAME or
DNAME redirections are followed. Otherwise, if a CNAME or DNAME
record is encountered while resolving, an error is returned.

--search=BOOL
Takes a boolean parameter. If true (the default), any specified
single-label hostnames will be searched in the domains configured
in the search domain list, if it is non-empty. Otherwise, the
search domain logic is disabled.

--raw[=payload|packet]
Dump the answer as binary data. If there is no argument or if the
argument is "payload", the payload of the packet is exported. If
the argument is "packet", the whole packet is dumped in wire
format, prefixed by length specified as a little-endian 64-bit
number. This format allows multiple packets to be dumped and
unambiguously parsed.

--legend=BOOL
Takes a boolean parameter. If true (the default), column headers
and meta information about the query response are shown. Otherwise,
this output is suppressed.

-h, --help
Print a short help text and exit.

--version
Print a short version string and exit.

--no-pager
Do not pipe output into a pager.

COMPATIBILITY WITH RESOLVCONF(8)
resolvectl is a multi-call binary. When invoked as "resolvconf"
(generally achieved by means of a symbolic link of this name to the
resolvectl binary) it is run in a limited resolvconf(8) compatibility
mode. It accepts mostly the same arguments and pushes all data into
systemd-resolved.service(8), similar to how dns and domain commands
operate. Note that systemd-resolved.service is the only supported
backend, which is different from other implementations of this command.
Note that not all operations supported by other implementations are
supported natively. Specifically:

-a
Registers per-interface DNS configuration data with
systemd-resolved. Expects a network interface name as only command
line argument. Reads resolv.conf(5) compatible DNS configuration
data from its standard input. Relevant fields are "nameserver" and
"domain"/"search". This command is mostly identical to invoking
resolvectl with a combination of dns and domain commands.

-d
Unregisters per-interface DNS configuration data with
systemd-resolved. This command is mostly identical to invoking
resolvectl revert.

-f
When specified -a and -d will not complain about missing network
interfaces and will silently execute no operation in that case.

-x
This switch for "exclusive" operation is supported only partially.
It is mapped to an additional configured search domain of "~." --
i.e. ensures that DNS traffic is preferably routed to the DNS
servers on this interface, unless there are other, more specific
domains configured on other interfaces.

-m, -p
These switches are not supported and are silently ignored.

-u, -I, -i, -l, -R, -r, -v, -V, --enable-updates, --disable-updates,
--are-updates-enabled
These switches are not supported and the command will fail if used.

See resolvconf(8) for details on this command line options.

BACKWARDS COMPATIBILITY WITH SYSTEMD-RESOLVE
resolvectl is a multi-call binary, which previously was named
"systemd-resolve" and used slightly different parameters. When it is
invoked as "systemd-resolve" (generally achieved by means of a symbolic
link of this name to the resolvectl binary), it runs in compatibility
mode. For details on the specific parameters and calling syntax, see
the output from systemd-resolve --help. Calling the binary as
"systemd-resolve" is deprecated and should only be done for backwards
compatibility. All current and new use should call the binary as
"resolvectl".

EXAMPLES
Example 1. Retrieve the addresses of the "www.0pointer.net" domain

$ resolvectl query www.0pointer.net
www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
85.214.157.71

-- Information acquired via protocol DNS in 611.6ms.
-- Data is authenticated: no

Example 2. Retrieve the domain of the "85.214.157.71" IP address

$ resolvectl query 85.214.157.71
85.214.157.71: gardel.0pointer.net

-- Information acquired via protocol DNS in 1.2997s.
-- Data is authenticated: no

Example 3. Retrieve the MX record of the "yahoo.com" domain

$ resolvectl --legend=no -t MX query yahoo.com
yahoo.com. IN MX 1 mta7.am0.yahoodns.net
yahoo.com. IN MX 1 mta6.am0.yahoodns.net
yahoo.com. IN MX 1 mta5.am0.yahoodns.net

Example 4. Resolve an SRV service

$ resolvectl service _xmpp-server._tcp gmail.com
_xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
173.194.210.125
alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
173.194.65.125
...

Example 5. Retrieve a PGP key

$ resolvectl openpgp zbyszek@fedoraproject.org
d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
...

Example 6. Retrieve a TLS key ("tcp" and ":443" could be skipped)

$ resolvectl tlsa tcp fedoraproject.org:443
_443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
-- Cert. usage: CA constraint
-- Selector: Full Certificate
-- Matching type: SHA-256

SEE ALSO
systemd(1), systemd-resolved.service(8), systemd.dnssd(5), systemd-
networkd.service(8), resolvconf(8)

NOTES
1. DNS-SD
https://tools.ietf.org/html/rfc6763

2. SRV
https://tools.ietf.org/html/rfc2782

3. OPENPGPKEY
https://tools.ietf.org/html/rfc7929

4. TLSA
https://tools.ietf.org/html/rfc6698

5. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795

6. Multicast DNS
https://www.ietf.org/rfc/rfc6762.txt

systemd 245 RESOLVECTL(1)

resolvectl

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