Realm
=====
[![GoDoc](https://godoc.org/github.com/brettlangdon/realm?status.svg)](https://godoc.org/github.com/brettlangdon/realm)

A simple non-recursive DNS server written in [go](https://golang.org).

## Installation
### Go get
```
go get -u github.com/brettlangdon/realm/cmd/...
```

### Build
```
git clone https://github.com/brettlangdon/realm
cd ./realm
make
```

## Usage
```
$ realm --help
usage: realm [--bind BIND] [ZONE [ZONE ...]]

positional arguments:
  zone                   DNS zone files to serve from this server

options:
  --bind BIND            [<host>]:<port> to bind too [default: :53]
  --help, -h             display this help and exit
```

### Zone file
To run a server you must have a DNS [zone file](https://en.wikipedia.org/wiki/Zone_file).

A simple example looks like the following:

```
$ORIGIN example.com.     ; designates the start of this zone file in the namespace
$TTL 1h                  ; default expiration time of all resource records without their own TTL value
example.com.  IN  SOA   ns.example.com. username.example.com. ( 2007120710 1d 2h 4w 1h )
example.com.  IN  NS    ns                    ; ns.example.com is a nameserver for example.com
example.com.  IN  NS    ns.somewhere.example. ; ns.somewhere.example is a backup nameserver for example.com
example.com.  IN  MX    10 mail.example.com.  ; mail.example.com is the mailserver for example.com
@             IN  MX    20 mail2.example.com. ; equivalent to above line, "@" represents zone origin
@             IN  MX    50 mail3              ; equivalent to above line, but using a relative host name
example.com.  IN  A     192.0.2.1             ; IPv4 address for example.com
              IN  AAAA  2001:db8:10::1        ; IPv6 address for example.com
ns            IN  A     192.0.2.2             ; IPv4 address for ns.example.com
              IN  AAAA  2001:db8:10::2        ; IPv6 address for ns.example.com
www           IN  CNAME example.com.          ; www.example.com is an alias for example.com
wwwtest       IN  CNAME www                   ; wwwtest.example.com is another alias for www.example.com
mail          IN  A     192.0.2.3             ; IPv4 address for mail.example.com
mail2         IN  A     192.0.2.4             ; IPv4 address for mail2.example.com
mail3         IN  A     192.0.2.5             ; IPv4 address for mail3.example.com
```

Example taken from [here](https://en.wikipedia.org/wiki/Zone_file#File_format).

### Starting the server
```
realm ./domain.zone
```

By default `realm` binds to port `53`, which usually requires root, so you may need to run `sudo realm ./domain.zone`.

You can also specify any number of zone files by providing multiple zone files.

```
realm ./first.domain.zone ./second.domain.zone
```