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GETNAMEINFO(1)              General Commands Manual             GETNAMEINFO(1)

NAME
     getnameinfo - resolve IP addresses and ports to host and service names

SYNOPSIS
     getnameinfo [-46FHNnrSu] [-f family] [-p port] [IP-address]

DESCRIPTION
     The getnameinfo utility resolves IP addresses and port numbers to
     hostnames and service names as if with the getnameinfo(3) library routine
     and formats them to standard output.

     The output is a single line of space-separated fields:

           hostname service

     Depending on the flags specified, the output may consist only of the
     hostname or service name, or their numeric representations.  By default,
     both are shown.

     Although getnameinfo may query the DNS or other sources for name
     resolution depending on the system's nsswitch.conf(5) configuration, it
     is not intended to replace DNS-specific tools like dig(1).

     The following options are available:

     -4          Restrict the lookup to IPv4 addresses only.

     -6          Restrict the lookup to IPv6 addresses only.

     -F          Suppress the fully-qualified domain name (FQDN).  This is
                 equivalent to the NI_NOFQDN flag in getnameinfo(3).

     -f          Specify an address family numerically or as a name, eg.
                 "inet".

     -H          Display only the hostname, omitting the service name.

     -N          Display the numeric service name instead of resolving to a
                 service name.  This is equivalent to the NI_NUMERICSERV flag
                 in getnameinfo(3).

     -n          Display the numeric host address instead of resolving to a
                 hostname.  This is equivalent to the NI_NUMERICHOST flag in
                 getnameinfo(3).

     -p port     Specify the port number to be used in the lookup.

     -r          Ensure that a name is returned.  If no name can be resolved,
                 an error is reported.  This is equivalent to the NI_NAMEREQD
                 flag in getnameinfo(3).

     -S          Display only the service name, omitting the hostname.

     -u          Use UDP instead of the default TCP.  This is equivalent to
                 the NI_DGRAM flag in getnameinfo(3).

EXIT STATUS
     The getnameinfo utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     Look up the hostname and service name for an IPv4 address:

           $ getnameinfo -4 -p 80 93.184.216.34
           example.com http

     Look up the numeric host and service for an IPv6 address:

           $ getnameinfo -nN -p 443 2606:2800:220:1:248:1893:25c8:1946
           2606:2800:220:1:248:1893:25c8:1946 443

     Resolve an address to its hostname but suppress the service name:

           $ getnameinfo -H -p 22 192.0.2.1
           example-host

     Resolve a hostname and service for a UDP connection:

           $ getnameinfo -u -p 53 198.51.100.2
           example-dns-server domain

SEE ALSO
     dig(1), getaddrinfo(1), getaddrinfo(3), getnameinfo(3), inet(3),
     hosts(5), nsswitch.conf(5)

NetBSD 11.99                   February 6, 2025                   NetBSD 11.99