diff options
| author | Xi Ruoyao <xry111@xry111.site> | 2023-09-14 16:48:46 +0800 |
|---|---|---|
| committer | Xi Ruoyao <xry111@xry111.site> | 2023-09-14 16:50:37 +0800 |
| commit | ba40e325667d24c3988ae5c0395c79a7fe73e6ea (patch) | |
| tree | 9586eee47b07c096907dde964118e5bf3fd53c87 /chapter09 | |
| parent | efd11134bb9bfa33f3c64aee634b2232bee571d3 (diff) | |
systemd: Use NSS modules provided by systemd in nsswitch.conf
It allows a simplification to /etc/hosts. Also correct some info about
FQDN in both sysv and systemd.
Diffstat (limited to 'chapter09')
| -rw-r--r-- | chapter09/network.xml | 22 | ||||
| -rw-r--r-- | chapter09/networkd.xml | 53 |
2 files changed, 39 insertions, 36 deletions
diff --git a/chapter09/network.xml b/chapter09/network.xml index c86edf56a..541ece699 100644 --- a/chapter09/network.xml +++ b/chapter09/network.xml @@ -178,9 +178,10 @@ EOF</userinput></screen> <secondary>/etc/hosts</secondary> </indexterm> - <para>Decide on the IP address, fully-qualified domain name (FQDN), and - possible aliases for use in the <filename>/etc/hosts</filename> file. The - syntax is:</para> + <para>Decide on a fully-qualified domain name (FQDN), and possible aliases + for use in the <filename>/etc/hosts</filename> file. If using static IP + addresses, you'll also need to decide on an IP address. The syntax + for a hosts file entry is:</para> <screen><literal>IP_address myhost.example.org aliases</literal></screen> @@ -197,11 +198,18 @@ EOF</userinput></screen> <para>x can be any number in the range 16-31. y can be any number in the range 0-255.</para> - <para>A valid private IP address could be 192.168.1.1. A valid FQDN for - this IP could be lfs.example.org.</para> + <para>A valid private IP address could be 192.168.1.1.</para> - <para>Even if not using a network card, a valid FQDN is still required. - This is necessary for certain programs to operate correctly.</para> + <para>If the computer is to be visible to the Internet, a valid FQDN + can be the domain name itself, or a string resulted by concatenating a + prefix (often the hostname) and the domain name with a <quote>.</quote> + character. And, you need to contact the domain provider to resolve the + FQDN to your public IP address.</para> + + <para>Even if the computer is not visible to the Internet, a FQDN is + still needed for certain programs, such as MTAs, to operate properly. + A special FQDN, <literal>localhost.localdomain</literal>, can be used + for this purpose.</para> <para>Create the <filename>/etc/hosts</filename> file by running:</para> diff --git a/chapter09/networkd.xml b/chapter09/networkd.xml index 43b7e7172..27f15e815 100644 --- a/chapter09/networkd.xml +++ b/chapter09/networkd.xml @@ -316,27 +316,18 @@ EOF</userinput></screen> <para>x can be any number in the range 16-31. y can be any number in the range 0-255.</para> - <para>A valid private IP address could be 192.168.1.1. A valid FQDN for - this IP could be lfs.example.org.</para> + <para>A valid private IP address could be 192.168.1.1.</para> - <para>Even if not using a network card, a valid FQDN is still required. - This is necessary for certain programs, such as MTAs, to operate properly.</para> + <para>If the computer is to be visible to the Internet, a valid FQDN + can be the domain name itself, or a string resulted by concatenating a + prefix (often the hostname) and the domain name with a <quote>.</quote> + character. And, you need to contact the domain provider to resolve the + FQDN to your public IP address.</para> -<!-- - <para>Create the /etc/hosts file using the following command:</para> - -<screen role="nodump"><userinput>cat > /etc/hosts << "EOF" -<literal># Begin /etc/hosts - -127.0.0.1 localhost.localdomain localhost -127.0.1.1 <replaceable><FQDN></replaceable> <replaceable><HOSTNAME></replaceable> -::1 localhost ip6-localhost ip6-loopback -ff02::1 ip6-allnodes -ff02::2 ip6-allrouters - -# End /etc/hosts</literal> -EOF</userinput></screen> ---> + <para>Even if the computer is not visible to the Internet, a FQDN is + still needed for certain programs, such as MTAs, to operate properly. + A special FQDN, <literal>localhost.localdomain</literal>, can be used + for this purpose.</para> <para>Create the <filename>/etc/hosts</filename> file using the following command:</para> @@ -344,28 +335,32 @@ EOF</userinput></screen> <screen><userinput>cat > /etc/hosts << "EOF" <literal># Begin /etc/hosts -127.0.0.1 localhost.localdomain localhost -127.0.1.1 <replaceable><FQDN></replaceable> <replaceable><HOSTNAME></replaceable> -<replaceable><192.168.0.2></replaceable> <replaceable><FQDN></replaceable> <replaceable><HOSTNAME></replaceable> <replaceable>[alias1] [alias2] ...</replaceable> -::1 localhost ip6-localhost ip6-loopback +<replaceable><192.168.0.2></replaceable> <replaceable><FQDN></replaceable> <replaceable>[alias1] [alias2] ...</replaceable> +::1 ip6-localhost ip6-loopback ff02::1 ip6-allnodes ff02::2 ip6-allrouters # End /etc/hosts</literal> EOF</userinput></screen> - <para>The <replaceable><192.168.0.2></replaceable>, - <replaceable><FQDN></replaceable>, and - <replaceable><HOSTNAME></replaceable> values need to be + <para>The <replaceable><192.168.0.2></replaceable> and + <replaceable><FQDN></replaceable> values need to be changed for specific uses or requirements (if assigned an IP address by a network/system administrator and the machine will be connected to an existing network). The optional alias name(s) can be omitted, and the <replaceable><192.168.0.2></replaceable> line can be omitted if you - are using a connection configured with DHCP or IPv6 Autoconfiguration.</para> + are using a connection configured with DHCP or IPv6 Autoconfiguration, + or using <literal>localhost.localdomain</literal> as the FQDN.</para> + + <para>The <filename>/etc/hostname</filename> does not contain entries + for <literal>localhost</literal>, + <literal>localhost.localdomain</literal>, or the hostname (without a + domain) because they are handled by the + <systemitem class='library'>myhostname</systemitem> NSS module, read + the man page <filename>nss-myhostname(8)</filename> for details.</para> <para>The ::1 entry is the IPv6 counterpart of 127.0.0.1 and represents - the IPv6 loopback interface. 127.0.1.1 is a loopback entry reserved - specifically for the FQDN.</para> + the IPv6 loopback interface.</para> </sect2> |