This is a script you run on a single master configuration file ( /etc/bind/si46.master ) that sets up all the real configurations for address allocation and host naming on a typical small network, for both IPv4 and IPv6. The si46.master file is a bind9 forward map file, with additional directives in comment sections that allow building configuration for DHCP service for IPv4, and a 'what people usually want' split-horizon DNS service, showing hosts on the network only to other hosts on the network, with those outside the network seeing only one or two chosen hosts.
It does not run any services, it just defines the configurations for the standard debian-based services. You run all your services in the standard way.
This script runs on a router, or a host that runs DNS and DHCP servers. if you have a canned router appliance that does not run real debian, then this is not useful. for example, I run my gateway on a raspberry pi, running raspbian. This is much more flexible/intuitive for linux oriented admins, but there is no UI, everything it done at the command line.
You should already have some background in bind/dhcp, etc... This script automates the tedium, but it does not help you understand the individual services.
If you want to be able to look at network traffic and have some idea who is talking to who, you need to map the addresses to human readable names. These are the services to do this. This script is for people who have configured bind and dhcp manually before, and find it tedious.
Using the standar linux tools as intended, you need to write the same information between 2 and 6 times. With si46ib9d, you write the information once, and the script creates all the other obvious copies for you.
While this sounds like a minor convenience for IPv4, in the IPv6 world it becomes more important because they like to renumber things. in IPv4 with a typical home network, you have a single public address, and then a natting firewall which means all your internal addresses are static ones you pick.
With IPv6, you normally do not NAT. So when your public firewall IP address changes (which it does a couple of times a year), all of the bind records need to be re-written. This script, whenever it is run, just reads the prefix from the network, and re-writes all the IPv6 records correctly.
A Minimum si46.master configuration is given below:
;DNS-Domain=example.com
;SOA fwgw hostmaster
IN NS fwgw.example.com.
fwgw IN A 123.142.254.10 ; public
;DNS-Forwarders=123.142.225.1,123.142.227.2
;DNS-Network=192.168.10/24
onehost IN A 3 ; MAC=52:54:00:f8:b5:26
As per bind documentation, a semi-colon (;) is used as a comment delimiter.
text on a line before a any semi-colon, is a part of a normal bind forward map.
Si46 directives happen in the comments. The directives are also case sensitive.
The first si46 directive is ;DNS-Domain, the value you set there is the domain you want to use for entire configuration. Here we are building a configuration for example.com. The second line is ;SOA. This line is used to build the Start Of Authority, a header needed for all the forward and reverse zones. Documentation of SOA records is available in bind documentation. Briefly, the elements are:
fwgw - the host on which the zone was created. (expands to: fwgw.example.com)
hostmaster - admin email address (expands to: hostmaster@example.com)
The rest of the SOA is given sensible defaults. Si46 generates the serial number from the linux time stamp (seconds since start of epoch.) and allows you to override the other settings (see si46.master.glorious for an example with overrides.)
IN NS fwgw.example.com.
All zones need a name server, so use the ones declared here. You must declare it with the full domain name (and incude the '.' at the end.) Next is the corresponding host entry for fwgw. The enty looks like a a normal bind forward A record, used to define an IPv4 address.
fwgw IN A 123.142.254.10 ; public
fwgw's public IPv4 address (since it is an A record) is set to 123.142.254.10 The 'public' decoration, after the semi-colon indicates that this record will be published to the world, and not just to internal users.
;DNS-Forwarders=123.142.225.1,123.142.227.2
The DNS-Forwarders directive is where you put your ISP's DNS Server addresses (or some other provider.) The configuration will be such that the server will answer requests for the local domain, refer to the Forwarders for names outside the domain, and cache the replies for internal users.
The next directive is to declare a network.
;DNS-Network=192.168.10/24
This means that: -- addresses that follow, if not complete, should be assumed to be in this network. -- a reverse map for this network will be created.
You may have noticed that the network in this case, is a 192.168... network.
This is a non-routable address range. There is an assumption that, for IPv4,
the firewall gateway is taking care of NAT.
So with all that out of the way, here is what you need to declare machines on your network:
onehost IN A 3 ; MAC=52:54:00:f8:b5:26
So there is a machine named 'onehost' whose MAC address is given. onehost's IP address will be 192.168.10.3. The DHCP configuration will be made for onehost to be always be given the same address, if asked. If IPv6 is enabled, the MAC address can also be used to calculate the Stateless autoconfiguration (SLAC) address, or for dhcpv6.
To make use of this configuration file, you need to have bind9 and isc-dhcp-server installed:
apt-get install bind9 bindutils isc-dhcp-server
#test to avoid overwriting real config:
si46ib9d -r ./si46.master.simple -w `pwd`
for the simple example, si46ib9d creates: named.conf, named.conf.options, named.conf.local, dbf.internal.example.com, dbf.public.example.com, dbr.192.168.10, dbr.192.168.9, dbr.empty-zones, dhcpd.conf, named.conf, named.conf.local, named.conf.options
#do syntax check of the setup:
named-checkconf -z named.conf
Once you are happy that the configuraion looks good, copy it to the standard /etc/bind location.
cp si46.master /etc/bind
Then you can invoke si46ib9d without arguments and it will place all the config files and zones under /etc/bind.
twohost IN A 4 ; MAC=51:54:e0:f3:b5:26
When you want to add hosts, you just add a single line per host, as per twohost above. Then re-run si46ib9d and the forward, reverse, and DHCP information will all be updated. This ends the walk-through the simplest case, IPv4 only.
Dealing with DHCP and guests.
FIXME: to come, see example in si46.example.glorious
My ISP has deployed IPv6 using the Rapid Deployment (RD) protocol.
Using DHCP extensions, the Router Advertisement Daemon (radvd) has been
configured to announce addresses whenever the ISP link is brought up.
Unlike IPv4, where networks inside are isolated from the outside via
Network Address Translation,
or addresses are permanently assigned, in IPv6, there is the notion of "rapid-renumbering"
and the addresses assigned by my ISP change from time to time.
Whenever the IPv6 network address changes, there is no NAT, so all the addresses on the internal zone have to change as well. With si46ib9d, I supply the following directives:
;DNS-Network=radvd
trestler IN A eth1 ; public
trestler IN AAAA 6rdif ; public
The DNS-Network directive makes the script consult /etc/radvd.conf to determine the network prefix in effect. Si46ib9d will assign addresses for all later host records in the file. The host entries that follow, instead of having an address, indicate the interface whose address should be used. Whenever the program is run, the interface and radvd.conf file information is refreshed, and the zones re-written completely.
ISC tools are the most popular ones, but they are built for running large corporate sites, and their configuration methods, allow an almost infinite configurability, and are quite intimidating in the number of decisions they ask. Further, they have grown somewhat organically over time, and have gotten a bit unwieldy.
This script uses a single data file, that looks a lot like an ISC forward zone file, but adds 'decorations' (directives hidden in zone file comments) to allow it to be used to build the entire configuration. It is also much more information dense, one can look at a few lines, at most a page, of configuration and understand the general setup.
The single data file is much simpler to maintain and is meant for editing by humans. Once the domain and network decorators are set, adding a new machine, is just a one line entry:
debvm IN A 3 ; MAC=52:54:00:f8:b5:26
The above line will create an entry for the machine named 'debvm' with the fixed IP address. In a DHCP and Bind configuration for IPv4 and IPv6, you need, for example, to enter a hostname:
-- in the IPv4 forward map for a domain, along with ip addr.
-- in the reverse map same is repeated.
-- in the IPv4 dhcp map have both hostname and address, as well as MAC.
-- in the IPv6 fwd map stateless auto config is calculated from MAC
-- in the IPv6 dhcp map has both hostname and address, as well as MAC.
So you have to enter the hostname, mac, and address between three and six times. This script eliminates that sort of repetitive drudgery. by picking a particular network design and user case, and making some assumptions:
-- The configuration is for a single domain.
-- for every forward address on a defined network,
make the obvious reverse record.
-- Create two ISC-Bind 9 views: internal, and public. by default,
all host records are internal. You need to decorate an entry with
public, to have the entry added to the public view.
-- @ (domain) records MX, TXT, NS, by default, are in all views.
-- there are no DNS keys or updates ´update none.´ Use SSH or
some other mechanism to distribute updates.
-- There is a main, flat network
-- currently, support RADVD - IPv6 Router Advertisement Daemon.
-- bind9 and bind9utils are installed, as per Debian wheezy.
to provide all the static domains in /etc/bind/db.* (0, 127, empty, etc...)
tool refers to these in their standard place.
These assumptions create a configuration which is likely suitable for many small businesses or (geeky!) homes. If you don't want a public view, do not run the configuration on a public facing server, and it will not be a problem. if a firewalling mistake grants an external user access to the internal network, they will only get the public view, which is still a benefit.
The script is can be run regularly to re-create zones when using a system with an ISP provided dynamic addresses, allocated by some mechanism such as DHCP. The one departure from making the si46.master file a valid forward zone is that one can place an interface address in place of an IP (4 or 6) address in the file, which is assumed to be on the machine where the script is run. If you can run the script on the router, then the dynamic addresses are automatically picked up.
-- need a way to put in real comments... ;# ?
-- Add named-checkzone -- Adding NS directive. have it build name server prolog from the tagged entries. -- Add the tail -f syslog to identify what to add to config. -- Adding auto-dhcp. ;DNS-Network 192.168.1.0 gateway=1 dhcp (dungeon|guests)=4 -- Run on other machines. This script works a lot better/more automagically if it is run on the gateway firewall. Many use an appliance as a firewall, rather than a real debian host. The script uses /etc/radvd.conf and the interface addresses on the gateway hosts to build the zone. It would be better if the script would notice, at a client level, parameters and use them, rather than have to run on the gateway.
-- Build whole named configuration. currently builds: named.conf.local, all fwd and rev zones, named.conf, named.conf.options, but not: zone.empty, db.0, db.127, db.root, etc... these files are pretty trivial, did not see the point, but if you do not create them, the checkconf remains reliant on /etc/bind.
-- Improve DHCPv4 automation pick an address range automatically. automatic guest addresses. add email notification for guests. add a donjeon mode... (wrong router?, wrong net?) for guests.
Other Stuff: Firewall Scripts included at no extra cost!
Have a look at the interfaces and rc*firewall scripts. They give an idea about how to set that up as well. In IPv4 you use NAT, but with IPv6, firewalls do not have to work so hard, you just limit what they can access with lists.
FIXME: - sysctl ip_forward ? -