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| SPDX-License-Identifier: LGPL-2.1+ |
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| <refentry id="nss-mymachines" conditional='ENABLE_NSS_MYMACHINES'> |
| |
| <refentryinfo> |
| <title>nss-mymachines</title> |
| <productname>systemd</productname> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>nss-mymachines</refentrytitle> |
| <manvolnum>8</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>nss-mymachines</refname> |
| <refname>libnss_mymachines.so.2</refname> |
| <refpurpose>Provide hostname resolution for local |
| container instances.</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <para><filename>libnss_mymachines.so.2</filename></para> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para><command>nss-mymachines</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of |
| the GNU C Library (<command>glibc</command>), providing hostname resolution for the names of containers running |
| locally that are registered with |
| <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. 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 |
| <option>--private-network</option> in |
| <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>). |
| Note that the name that is resolved is the one registered with <command>systemd-machined</command>, which |
| may be different than the hostname configured inside of the container.</para> |
| |
| <para>The module also provides name resolution for user and group identifiers mapped to containers. All names from |
| the range allocated to a given container <replaceable>container</replaceable> are exposed on the host as |
| <literal>vu-<replaceable>container</replaceable>-<replaceable>uid</replaceable></literal> and |
| <literal>vg-<replaceable>container</replaceable>-<replaceable>gid</replaceable></literal> (see example below). This |
| functionality only applies to containers using user namespacing (see the description of |
| <option>--private-users</option> in |
| <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>).</para> |
| |
| <para>To activate the NSS module, add <literal>mymachines</literal> to the lines starting with |
| <literal>hosts:</literal>, <literal>passwd:</literal> and <literal>group:</literal> in |
| <filename>/etc/nsswitch.conf</filename>.</para> |
| |
| <para>It is recommended to place <literal>mymachines</literal> after the <literal>files</literal> or |
| <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines to make sure that its mappings |
| are preferred over other resolvers such as DNS, but so that <filename>/etc/hosts</filename>, |
| <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Configuration in <filename>/etc/nsswitch.conf</filename></title> |
| |
| <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables |
| <command>nss-mymachines</command> correctly:</para> |
| |
| <!-- synchronize with other nss-* man pages and factory/etc/nsswitch.conf --> |
| <programlisting>passwd: compat <command>mymachines</command> systemd |
| group: compat <command>mymachines</command> systemd |
| shadow: compat |
| |
| hosts: files <command>mymachines</command> resolve [!UNAVAIL=return] dns myhostname |
| networks: files |
| |
| protocols: db files |
| services: db files |
| ethers: db files |
| rpc: db files |
| |
| netgroup: nis</programlisting> |
| |
| </refsect1> |
| |
| <refsect1> |
| <title>Mappings provided by <filename>nss-mymachines</filename></title> |
| |
| <para>The container <literal>rawhide</literal> is spawned using |
| <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>: |
| </para> |
| |
| <programlisting># 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 '^vu-rawhide' |
| 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. |
| </programlisting> |
| </refsect1> |
| |
| <refsect1> |
| <title>See Also</title> |
| <para> |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
| <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |