NAME¶
resolvectl, resolvconf - 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 addresses 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" hostname or all data from /etc/hosts.
COMMANDS¶
query HOSTNAME|ADDRESS...
Resolve domain names, as well as IPv4 and IPv6 addresses.
When used in conjunction with
--type= or
--class= (see below),
resolves low-level DNS resource records.
If a single-label domain name is specified it is searched for
according to the configured search domains — unless
--search=no or --type=/--class= are specified, both of
which turn this logic off.
If an international domain name is specified, it is automatically
translated according to IDNA rules when resolved via classic DNS —
but not for look-ups via MulticastDNS or LLMNR. If
--type=/--class= is used IDNA translation is turned off and
domain names are processed as specified.
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
resource record 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 resource
records, see RFC 7929[3]. 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 resource
records, see RFC 6698[4]. 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. Each address can optionally take a port
number separated with ":", a network interface name or index
separated with "%", and a Server Name Indication (SNI) separated
with "#". When IPv6 address is specified with a port number, then
the address must be in the square brackets. That is, the acceptable full
formats are "111.222.333.444:9953%ifname#example.com" for IPv4 and
"[1111:2222::3333]:9953%ifname#example.com" for IPv6. 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.
monitor
Show a continuous stream of local client resolution
queries and their responses. Whenever a local query is completed the query's
DNS resource lookup key and resource records are shown. Note that this
displays queries issued locally only, and does not immediately relate to DNS
requests submitted to configured DNS servers or the LLMNR or MulticastDNS
zones, as lookups may be answered from the local cache, or might result in
multiple DNS transactions (for example to validate DNSSEC information). If
CNAME/CNAME redirection chains are followed, a separate query will be
displayed for each element of the chain. Use --json= to enable JSON
output.
log-level [LEVEL]
If no argument is given, print the current log level of
the manager. If an optional argument
LEVEL is provided, then the
command changes the current log level of the manager to
LEVEL (accepts
the same values as
--log-level= described in
systemd(1)).
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/resolved.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
When used in conjunction with the
query command,
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.
Without these options resolvectl query provides high-level
domain name to address and address to domain name resolution. With these
options it provides low-level DNS resource record resolution. The search
domain logic is automatically turned off when these options are used, i.e.
specified domain names need to be fully qualified domain names. Moreover,
IDNA internal domain name translation is turned off as well, i.e.
international domain names should be specified in "xn--..."
notation, unless look-up in MulticastDNS/LLMNR is desired, in which case
UTF-8 characters should be used.
--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.
--validate=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), DNSSEC validation is applied as usual
— under the condition that it is enabled for the network and for
systemd-resolved.service as a whole. If false, DNSSEC validation is disabled
for the specific query, regardless of whether it is enabled for the network or
in the service. Note that setting this option to true does not force DNSSEC
validation on systems/networks where DNSSEC is turned off. This option is only
suitable to turn off such validation where otherwise enabled, not enable
validation where otherwise disabled.
--synthesize=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), select domains are resolved on the local
system, among them "localhost", "_gateway",
"_outbound", "_localdnsstub" and
"_localdnsproxy" or entries from /etc/hosts. If false these domains
are not resolved locally, and either fail (in case of "localhost",
"_gateway" or "_outbound" and suchlike) or go to the
network via regular DNS/mDNS/LLMNR lookups (in case of /etc/hosts
entries).
--cache=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), lookups use the local DNS resource record
cache. If false, lookups are routed to the network instead, regardless if
already available in the local cache.
--zone=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), lookups are answered from locally
registered LLMNR or mDNS resource records, if defined. If false, locally
registered LLMNR/mDNS records are not considered for the lookup request.
--trust-anchor=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), lookups for DS and DNSKEY are answered
from the local DNSSEC trust anchors if possible. If false, the local trust
store is not considered for the lookup request.
--network=BOOL
Takes a boolean parameter; used in conjunction with
query. If true (the default), lookups are answered via DNS, LLMNR or
mDNS network requests if they cannot be synthesized locally, or be answered
from the local cache, zone or trust anchors (see above). If false, the request
is not answered from the network and will thus fail if none of the indicated
sources can answer them.
--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. Note that this option has no effect if --type= is used
(see above), in which case the search domain logic is unconditionally turned
off.
--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.
--json=MODE
Shows output formatted as JSON. Expects one of
"short" (for the shortest possible output without any redundant
whitespace or line breaks), "pretty" (for a pretty version of the
same, with indentation and line breaks) or "off" (to turn off JSON
output, the default).
-j
Short for --json=auto
--no-pager
Do not pipe output into a pager.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
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.
/etc/resolv.conf will only be updated with servers added with this
command when /etc/resolv.conf is a symlink to
/run/systemd/resolve/resolv.conf, and not a static file. See the discussion
of /etc/resolv.conf handling in systemd-resolved.service(8).
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 those command line
options.
EXAMPLES¶
Example 1. Retrieve the addresses of the
"www.0pointer.net" domain (A and AAAA resource records)
$ 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 (PTR resource record)
$ 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 (OPENPGP resource
record)
$ resolvectl openpgp zbyszek@fedoraproject.org
d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
...
Example 6. Retrieve a TLS key (TLSA resource
record)
$ 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
"tcp" and ":443" are optional and could be
skipped.
NOTES¶
- 1.
- DNS-SD
- 2.
- SRV
- 3.
- RFC 7929
- 4.
- RFC 6698
- 5.
- Link-Local Multicast Name Resolution
- 6.
- Multicast DNS