Ubuntu Manpage: systemd-resolve - Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and

Provided by: systemd_237-3ubuntu10.57_amd64

NAME

       systemd-resolve - Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and
       services

SYNOPSIS

       systemd-resolve [OPTIONS...] HOSTNAME...

       systemd-resolve [OPTIONS...] ADDRESS...

       systemd-resolve [OPTIONS...] --type=TYPE DOMAIN...

       systemd-resolve [OPTIONS...] --service [[NAME] TYPE] DOMAIN

       systemd-resolve [OPTIONS...] --openpgp USER@DOMAIN

       systemd-resolve [OPTIONS...] --tlsa DOMAIN[:PORT]

       systemd-resolve [OPTIONS...] --statistics

       systemd-resolve [OPTIONS...] --reset-statistics

DESCRIPTION

systemd-resolve 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.

The --type= switch may be used to specify a DNS resource record type (A, AAAA, SOA, MX,
...) in order to request a specific DNS resource record, instead of the address or reverse
address lookups. The special value "help" may be used to list known values.

The --service switch may be used to resolve SRV[1] and DNS-SD[2] services (see below). In
this mode, between one and three arguments are required. 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).

The --openpgp switch may be used to query PGP keys stored as OPENPGPKEY[3] resource
records. When this option is specified one or more e-mail address must be specified.

The --tlsa switch maybe be used to query TLS public keys stored as TLSA[4] resource
records. When this option is specified one or more domain names must be specified.

The --statistics switch may be used to show resolver statistics, including information
about the number of successful and failed DNSSEC validations.

The --reset-statistics may be used to reset various statistics counters maintained the
resolver, including those shown in the --statistics output. This operation requires root
privileges.

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
Enables service resolution. This enables DNS-SD and simple SRV service resolution,
depending on the specified list of parameters (see above).

--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.

--openpgp
Enables OPENPGPKEY resource record resolution (see above). Specified e-mail addresses
are converted to the corresponding DNS domain name, and any OPENPGPKEY keys are
printed.

--tlsa
Enables TLSA resource record resolution (see above). 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 an argument
after --tlsa, otherwise tcp will be used.

--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.

--statistics
If specified general resolver statistics are shown, 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.

--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.

--status
Shows the global and per-link DNS settings in currently in effect.

--set-dns=SERVER, --set-domain=DOMAIN, --set-llmnr=MODE, --set-mdns=MODE,
--set-dnssec=MODE, --set-nta=DOMAIN
Set per-interface DNS configuration. These switches may be used to configure various
DNS settings for network interfaces that aren't managed by systemd-
networkd.service(8). (These commands will fail when used on interfaces that are
managed by systemd-networkd, please configure their DNS settings directly inside the
.network files instead.) These switches may be used to inform systemd-resolved about
per-interface DNS configuration determined through external means. Multiple of these
switches may be passed on a single invocation of systemd-resolve in order to set
multiple configuration options at once. If any of these switches is used, it must be
combined with --interface= to indicate the network interface the new DNS configuration
belongs to. The --set-dns= option expects an IPv4 or IPv6 address specification of a
DNS server to use, and may be used multiple times to define multiple servers for the
same interface. The --set-domain= option expects a valid DNS domain, possibly prefixed
with "~", and configures a per-interface search or route-only domain. It may be used
multiple times to configure multiple such domains. The --set-llmnr=, --set-mdns= and
--set-dnssec= options may be used to configure the per-interface LLMNR, MulticastDNS
and DNSSEC settings. Finally, --set-nta= may be used to configure additional
per-interface DNSSEC NTA domains and may also be used multiple times. For details
about these settings, their possible values and their effect, see the corresponding
options in systemd.network(5).

--revert
Revert the per-interface DNS configuration. This option must be combined with
--interface= to indicate the network interface the DNS configuration shall be reverted
on. If the DNS configuration is reverted all per-interface DNS setting are reset to
their defaults, undoing all effects of --set-dns=, --set-domain=, --set-llmnr=,
--set-mdns=, --set-dnssec=, --set-nta=. Note that when a network interface disappears
all configuration is lost automatically, an explicit reverting is not necessary in
that case.

-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.

EXAMPLES

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

           $ systemd-resolve 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

           $ systemd-resolve 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

           $ systemd-resolve -t MX yahoo.com --legend=no
           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

           $ systemd-resolve --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

           $ systemd-resolve --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)

           $ systemd-resolve --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

NOTES