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NSS-MYMACHINES(8)              nss-mymachines              NSS-MYMACHINES(8)

NAME         top

       nss-mymachines, - Hostname resolution for
       local container instances

SYNOPSIS         top

DESCRIPTION         top

       nss-mymachines is a plug-in module for the GNU Name Service Switch
       (NSS) functionality of the GNU C Library (glibc), providing hostname
       resolution for the names of containers running locally that are
       registered with systemd-machined.service(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 --private-network in
       systemd-nspawn(1)). Note that the name that is resolved is the one
       registered with systemd-machined, which may be different than the
       hostname configured inside of the container.

       To activate the NSS module, add "mymachines" to the line starting
       with "hosts:" in /etc/nsswitch.conf.

       It is recommended to place "mymachines" after the "files" or "compat"
       entry of the /etc/nsswitch.conf line to make sure that its mappings
       are preferred over other resolvers such as DNS, but so that
       /etc/hosts based mappings take precedence.


       Here is an example /etc/nsswitch.conf file that enables
       nss-mymachines correctly:

           passwd:         compat systemd
           group:          compat systemd
           shadow:         compat

           hosts:          mymachines resolve [!UNAVAIL=return] myhostname files dns
           networks:       files

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

           netgroup:       nis


       The container "rawhide" is spawned using systemd-nspawn(1):

           # 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
           rawhide container systemd-nspawn fedora 30 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 ( 56(84) bytes of data.
           64 bytes from ( 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 brd 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.

SEE ALSO         top

       systemd(1), systemd-machined.service(8), machinectl(1),
       nss-systemd(8), nss-resolve(8), nss-myhostname(8), nsswitch.conf(5),

COLOPHON         top

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systemd 246                                                NSS-MYMACHINES(8)

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