systemd Developer Lennart Poettering lennart@poettering.net systemd-resolve 1 systemd-resolve resolvconf Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services; introspect and reconfigure the DNS resolver 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 systemd-resolve OPTIONS --flush-caches systemd-resolve OPTIONS --reset-server-features systemd-resolve OPTIONS --status systemd-resolve OPTIONS --set-dns=SERVER --set-domain=DOMAIN --set-llmnr=MODE --set-mdns=MODE --set-dnssec=MODE --set-nta=DOMAIN systemd-resolve OPTIONS --revert resolvconf OPTIONS -a INTERFACE < FILE resolvconf OPTIONS -d INTERFACE systemd-resolve may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource records and services with the systemd-resolved.service8 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 and DNS-SD 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 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 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. -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), llmnr-ipv4, llmnr-ipv6 (LLMNR via the indicated underlying IP protocols), mdns (Multicast DNS), 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.service8. (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.network5. --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. systemd-resolve is a multi-call binary. When invoked as resolvconf (generally achieved by means of a symbolic link of this name to the systemd-resolve binary) it is run in a limited resolvconf8 compatibility mode. It accepts mostly the same arguments and pushes all data into systemd-resolved.service8, similar to how --set-dns= and --set-domain= 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.conf5 compatible DNS configuration data from its standard input. Relevant fields are nameserver and domain/search. This command is mostly identical to invoking systemd-resolve with a combination of --set-dns= and --set-domain=. -d Unregisters per-interface DNS configuration data with systemd-resolved. This command is mostly identical to invoking systemd-resolve with --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 resolvconf8 for details on this command line options. $ 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 $ 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 $ 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 $ 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 … $ systemd-resolve --openpgp zbyszek@fedoraproject.org d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs … $ 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 systemd1, systemd-resolved.service8, systemd.dnssd5, systemd-networkd.service8, resolvconf8