= pvl-hosts =

DNS/DHCP hosts management/integration for ISC bind9 and dhcpd.

Also includes network SNMP discovery.

== Hosts ==
The `pvl.hosts-*` tools read hosts files as input, which have an ini format, using section names as hostnames to configure attributes for that host:

    [foo]
        ip          = 192.0.2.1
        ethernet    = 00:11:22:33:44:55

    [bar]
        ip          = 192.0.2.2
        ethernet    = 01:23:45:67:89:ab

The domain name for a host is determined from the basename of the config file, so this example file would generate something like the following output for use in a `zone "test" { ... }` zonefile:
    
    $ bin/pvl.hosts-forward etc/hosts/example.com 
    foo                               A     192.0.2.1
    bar                               A     192.0.2.2

And correspondingly, the reverse zone for 192.0.2.0/24

    $ bin/pvl.hosts-reverse --reverse-zone=192.0.2 etc/hosts/example.com
    1                                 PTR   foo.example.com.
    2                                 PTR   bar.example.com.

And the associated DHCP hosts:

    $ bin/pvl.hosts-dhcp etc/hosts/example.com 
    host foo {
        option host-name foo;
        hardware ethernet 00:11:22:33:44:55;
        fixed-address 192.0.2.1;
    }

    host bar {
        option host-name bar;
        hardware ethernet 01:23:45:67:89:ab;
        fixed-address 192.0.2.2;
    }

=== Include directories ===
Host configs can be included:

    $ cat etc/hosts/test/test
    include = test.d/

    $ cat etc/hosts/test/test.d/foo 
    ip = 192.0.2.1

    $ cat etc/hosts/test/test.d/bar 
    ip = 192.0.2.2

    $ bin/pvl.hosts-forward etc/hosts/test/test
    foo                               A     192.0.2.1
    bar                               A     192.0.2.2

And an entire directory of hosts-files, containing sub-domains, can be given:

    $ ls etc/hosts/test/
    asdf.test  test  test.d

    $ cat etc/hosts/test/asdf.test 
    [quux]
        ip  = 192.0.2.5

    $ bin/pvl.hosts-forward etc/hosts/test/
    foo                               A     192.0.2.1
    bar                               A     192.0.2.2
    quux.asdf                         A     192.0.2.5

Note that the (include) directory name itself is NOT treated as a domain name. However, the file names which are included are.

Including a directory of files is equivalent to substituiting each file as a named section at the level of the include = statement. Note that this means that included files are treated directly as host definitions, IOW, you should NOT include a section name in an included host file unless you want to declare an additional subdomain:

    $ cat etc/hosts/wrong.test 
    include = wrong.d/
    
    $ etc/hosts/wrong.d/host
    [host]
        ip  = 192.0.2.6

Using the --root-zone option to generate the full FQDN for the host:

    $ bin/pvl.hosts-forward --root-zone etc/hosts/wrong.test 
    host.host.wrong.test              A     192.0.2.6

=== Host aliases ===
Hosts can specify DNS aliases:

    [foo]
        ip          = 127.0.0.1
        alias       = test1

    [bar]
        ip          = 127.0.0.2
        alias       = test2

    $ bin/pvl.hosts-forward --forward-zone alias.test etc/hosts/alias.test 
    foo                               A     127.0.0.1
    test1                             CNAME foo
    bar                               A     127.0.0.2
    test2                             CNAME bar

=== Generated hosts ===
The hosts file format supports something similar to bind9's $GENERATE directive for hosts:

    [asdf{1-3}]
        ip  = 10.100.100.$

    $ bin/pvl.hosts-dns --forward-zone=asdf etc/hosts/asdf 
    asdf1@asdf                        A     10.100.100.1
    asdf2@asdf                        A     10.100.100.2
    asdf3@asdf                        A     10.100.100.3

Note that the generate directives are interpreted and compiled directly by pvl.hosts. 

Most of the $GENERATE options should be supported, with a little clever hackery:

    [asdf{1-5/2}{0,2}]
       ip  = 10.100.100.$${10}

    $ bin/pvl.hosts-dns --forward-zone=asdf2 etc/hosts/asdf2
    asdf01@asdf2                      A     10.100.100.11
    asdf03@asdf2                      A     10.100.100.13
    asdf05@asdf2                      A     10.100.100.15

This feature can be used for generating reverse delegations:

    [foo-{240-247}]
        forward =
        reverse = $.240/29.0.0.10.in-addr.arpa
        ip      = 10.0.0.$
    
    $ bin/pvl.hosts-dns --reverse-zone=10 etc/hosts/reverse 
    240.0.0                           CNAME 240.240/29.0.0.10.in-addr.arpa.
    241.0.0                           CNAME 241.240/29.0.0.10.in-addr.arpa.
    242.0.0                           CNAME 242.240/29.0.0.10.in-addr.arpa.
    243.0.0                           CNAME 243.240/29.0.0.10.in-addr.arpa.
    244.0.0                           CNAME 244.240/29.0.0.10.in-addr.arpa.
    245.0.0                           CNAME 245.240/29.0.0.10.in-addr.arpa.
    246.0.0                           CNAME 246.240/29.0.0.10.in-addr.arpa.
    247.0.0                           CNAME 247.240/29.0.0.10.in-addr.arpa.

=== DHCP Options ===
The hosts need not specify any fixed ip address, leaving IP address allocation to dhcpd:

    [foo]
        ethernet    = 00:11:22:33:44:55 
    
    $ bin/pvl.hosts-dhcp etc/hosts/dhcp1 
    host foo {
        option host-name foo;
        hardware ethernet 00:11:22:33:44:55;
    }

=== DHCP Boot options ===
The hosts can specify DHCP boot server/file options:

    [foo]
        ethernet    = 00:11:22:33:44:55
        boot        = boot.lan:debian/wheezy/pxelinux.0

    $ bin/pvl.hosts-dhcp etc/hosts/boot.dhcp 
    host foo {
        option host-name foo;
        hardware ethernet 00:11:22:33:44:55;
        next-server boot.lan;
        filename debian/wheezy/pxelinux.0;
    }

=== DHCP hosts in multiple subnets/domains ===
A host with different interfaces in multiple domains must specify unique interface names:

    [foo.dhcp]
        [[asdf]]
            ip              = 10.1.0.1
            ethernet.eth1   = 00:11:22:33:44:55

    [bar.dhcp]
        [[asdf]]
            ip              = 10.2.0.1
            ethernet.eth2   = 55:44:33:22:11:00

    $ bin/pvl.hosts-dhcp etc/hosts/dhcp2 
    host asdf-eth1 {
        option host-name asdf;
        hardware ethernet 00:11:22:33:44:55;
        fixed-address 10.1.0.1;
    }

    host asdf-eth2 {
        option host-name asdf;
        hardware ethernet 55:44:33:22:11:00;
        fixed-address 10.2.0.1;
    }