'\" t
.TH "NSS\-MYMACHINES" "8" "" "systemd 247" "nss-mymachines"
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.SH "NAME"
nss-mymachines, libnss_mymachines.so.2 \- Hostname resolution for local container instances
.SH "SYNOPSIS"
.PP
libnss_mymachines\&.so\&.2
.SH "DESCRIPTION"
.PP
\fBnss\-mymachines\fR
is a plug\-in module for the GNU Name Service Switch (NSS) functionality of the GNU C Library (\fBglibc\fR), providing hostname resolution for the names of containers running locally that are registered with
\fBsystemd-machined.service\fR(8)\&. The container names are resolved to the IP addresses of the specific container, ordered by their scope\&. This functionality only applies to containers using network namespacing (see the description of
\fB\-\-private\-network\fR
in
\fBsystemd-nspawn\fR(1))\&. Note that the name that is resolved is the one registered with
\fBsystemd\-machined\fR, which may be different than the hostname configured inside of the container\&.
.PP
To activate the NSS module, add
"mymachines"
to the line starting with
"hosts:"
in
/etc/nsswitch\&.conf\&.
.PP
It is recommended to place
"mymachines"
before the
"resolve"
or
"dns"
entry of the
"hosts:"
line of
/etc/nsswitch\&.conf
in order to make sure that its mappings are preferred over other resolvers such as DNS\&.
.SH "CONFIGURATION IN /ETC/NSSWITCH\&.CONF"
.PP
Here is an example
/etc/nsswitch\&.conf
file that enables
\fBnss\-mymachines\fR
correctly:
.sp
.if n \{\
.RS 4
.\}
.nf
passwd:         compat systemd
group:          compat [SUCCESS=merge] systemd
shadow:         compat

hosts:          \fBmymachines\fR resolve [!UNAVAIL=return] files myhostname dns
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis
.fi
.if n \{\
.RE
.\}
.SH "EXAMPLE: MAPPINGS PROVIDED BY NSS\-MYMACHINES"
.PP
The container
"rawhide"
is spawned using
\fBsystemd-nspawn\fR(1):
.sp
.if n \{\
.RS 4
.\}
.nf
# systemd\-nspawn \-M rawhide \-\-boot \-\-network\-veth \-\-private\-users=pick
Spawning container rawhide on /var/lib/machines/rawhide\&.
Selected user namespace base 20119552 and range 65536\&.
\&.\&.\&.

$ machinectl \-\-max\-addresses=3
MACHINE CLASS     SERVICE        OS     VERSION ADDRESSES
rawhide container systemd\-nspawn fedora 30      169\&.254\&.40\&.164 fe80::94aa:3aff:fe7b:d4b9

$ ping \-c1 rawhide
PING rawhide(fe80::94aa:3aff:fe7b:d4b9%ve\-rawhide (fe80::94aa:3aff:fe7b:d4b9%ve\-rawhide)) 56 data bytes
64 bytes from fe80::94aa:3aff:fe7b:d4b9%ve\-rawhide (fe80::94aa:3aff:fe7b:d4b9%ve\-rawhide): icmp_seq=1 ttl=64 time=0\&.045 ms
\&.\&.\&.
$ ping \-c1 \-4 rawhide
PING rawhide (169\&.254\&.40\&.164) 56(84) bytes of data\&.
64 bytes from 169\&.254\&.40\&.164 (169\&.254\&.40\&.164): icmp_seq=1 ttl=64 time=0\&.064 ms
\&.\&.\&.

# machinectl shell rawhide /sbin/ip a
Connected to machine rawhide\&. Press ^] three times within 1s to exit session\&.
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    \&.\&.\&.
2: host0@if21: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 96:aa:3a:7b:d4:b9 brd ff:ff:ff:ff:ff:ff link\-netnsid 0
    inet 169\&.254\&.40\&.164/16 brd 169\&.254\&.255\&.255 scope link host0
       valid_lft forever preferred_lft forever
    inet6 fe80::94aa:3aff:fe7b:d4b9/64 scope link
       valid_lft forever preferred_lft forever
Connection to machine rawhide terminated\&.
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsystemd-machined.service\fR(8),
\fBmachinectl\fR(1),
\fBnss-systemd\fR(8),
\fBnss-resolve\fR(8),
\fBnss-myhostname\fR(8),
\fBnsswitch.conf\fR(5),
\fBgetent\fR(1)