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Dd February 6, 2025
Dt GETNAMEINFO 1
Os
Sh NAME
Nm getnameinfo
Nd resolve IP addresses and ports to host and service names
Sh SYNOPSIS
Nm
Op Fl 46FHNnrSu
Op Fl f Ar family
Op Fl p Ar port
Op Ar IP-address
Sh DESCRIPTION
The
Nm
utility resolves IP addresses and port numbers to hostnames and service names
as if with the
Xr getnameinfo 3
library routine and formats them to standard output.
Pp
The output is a single line of space-separated fields:
Pp
Dl hostname service
Pp
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.
Pp
Although
Nm
may query the DNS or other sources for name resolution depending on the
system's
Xr nsswitch.conf 5
configuration, it is not intended to replace DNS-specific tools like
Xr dig 1 .
Pp
The following options are available:
Bl -tag -width Fl
It Fl 4
Restrict the lookup to IPv4 addresses only.
It Fl 6
Restrict the lookup to IPv6 addresses only.
It Fl F
Suppress the fully-qualified domain name (FQDN).
This is equivalent to the
Dv NI_NOFQDN
flag in
Xr getnameinfo 3 .
It Fl f
Specify an address family numerically or as a name, eg.
Dq inet .
It Fl H
Display only the hostname, omitting the service name.
It Fl N
Display the numeric service name instead of resolving to a service name.
This is equivalent to the
Dv NI_NUMERICSERV
flag in
Xr getnameinfo 3 .
It Fl n
Display the numeric host address instead of resolving to a hostname.
This is equivalent to the
Dv NI_NUMERICHOST
flag in
Xr getnameinfo 3 .
It Fl p Ar port
Specify the port number to be used in the lookup.
It Fl r
Ensure that a name is returned.
If no name can be resolved, an error is reported.
This is equivalent to the
Dv NI_NAMEREQD
flag in
Xr getnameinfo 3 .
It Fl S
Display only the service name, omitting the hostname.
It Fl u
Use UDP instead of the default TCP.
This is equivalent to the
Dv NI_DGRAM
flag in
Xr getnameinfo 3 .
El
Sh EXIT STATUS
Ex -std getnameinfo
Sh EXAMPLES
Look up the hostname and service name for an IPv4 address:
Bd -literal -offset indent
$ getnameinfo -4 -p 80 93.184.216.34
example.com http
Ed
Pp
Look up the numeric host and service for an IPv6 address:
Bd -literal -offset indent
$ getnameinfo -nN -p 443 2606:2800:220:1:248:1893:25c8:1946
2606:2800:220:1:248:1893:25c8:1946 443
Ed
Pp
Resolve an address to its hostname but suppress the service name:
Bd -literal -offset indent
$ getnameinfo -H -p 22 192.0.2.1
example-host
Ed
Pp
Resolve a hostname and service for a UDP connection:
Bd -literal -offset indent
$ getnameinfo -u -p 53 198.51.100.2
example-dns-server domain
Ed
Sh SEE ALSO
Xr dig 1 ,
Xr getaddrinfo 1 ,
Xr getaddrinfo 3 ,
Xr getnameinfo 3 ,
Xr inet 3 ,
Xr hosts 5 ,
Xr nsswitch.conf 5

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