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'\" t
.TH "NSS\-MYMACHINES" "8" "" "systemd 241" "nss-mymachines"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
nss-mymachines, libnss_mymachines.so.2 \- Provide 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
The module also provides name resolution for user and group identifiers mapped to containers\&. All names from the range allocated to a given container
\fIcontainer\fR
are exposed on the host as
"vu\-\fIcontainer\fR\-\fIuid\fR"
and
"vg\-\fIcontainer\fR\-\fIgid\fR"
(see example below)\&. This functionality only applies to containers using user namespacing (see the description of
\fB\-\-private\-users\fR
in
\fBsystemd-nspawn\fR(1))\&.
.PP
To activate the NSS module, add
"mymachines"
to the lines starting with
"hosts:",
"passwd:"
and
"group:"
in
/etc/nsswitch\&.conf\&.
.PP
It is recommended to place
"mymachines"
after the
"files"
or
"compat"
entry of the
/etc/nsswitch\&.conf
lines to make sure that its mappings are preferred over other resolvers such as DNS, but so that
/etc/hosts,
/etc/passwd
and
/etc/group
based mappings take precedence\&.
.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 \fBmymachines\fR systemd
group: compat \fBmymachines\fR systemd
shadow: compat
hosts: files \fBmymachines\fR resolve [!UNAVAIL=return] dns myhostname
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
.fi
.if n \{\
.RE
.\}
.SH "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
$ getent passwd vu\-rawhide\-0 vu\-rawhide\-81
vu\-rawhide\-0:*:20119552:65534:vu\-rawhide\-0:/:/sbin/nologin
vu\-rawhide\-81:*:20119633:65534:vu\-rawhide\-81:/:/sbin/nologin
$ getent group vg\-rawhide\-0 vg\-rawhide\-81
vg\-rawhide\-0:*:20119552:
vg\-rawhide\-81:*:20119633:
$ ps \-o user:15,pid,tty,command \-e|grep \*(Aq^vu\-rawhide\*(Aq
vu\-rawhide\-0 692 ? /usr/lib/systemd/systemd
vu\-rawhide\-0 731 ? /usr/lib/systemd/systemd\-journald
vu\-rawhide\-192 734 ? /usr/lib/systemd/systemd\-networkd
vu\-rawhide\-193 738 ? /usr/lib/systemd/systemd\-resolved
vu\-rawhide\-0 742 ? /usr/lib/systemd/systemd\-logind
vu\-rawhide\-81 744 ? /usr/bin/dbus\-daemon \-\-system \-\-address=systemd: \-\-nofork \-\-nopidfile \-\-systemd\-activation \-\-syslog\-only
vu\-rawhide\-0 746 ? /usr/sbin/sshd \-D \&.\&.\&.
vu\-rawhide\-0 752 ? /usr/lib/systemd/systemd \-\-user
vu\-rawhide\-0 753 ? (sd\-pam)
vu\-rawhide\-0 1628 ? login \-\- zbyszek
vu\-rawhide\-1000 1630 ? /usr/lib/systemd/systemd \-\-user
vu\-rawhide\-1000 1631 ? (sd\-pam)
vu\-rawhide\-1000 1637 pts/8 \-zsh
$ 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)
|
