update

dnsmasq/readme.md

@@ -4,12 +4,22 @@
 
 ![logo](https://i.imgur.com/SOa4kRd.png)
 
-# Purpose
+# Purpose & Overview
 
 Lightweight DHCP and DNS server.
 
 * [Official site](http://www.thekelleys.org.uk/dnsmasq/doc.html)
-* [Arch wik](https://wiki.archlinux.org/index.php/dnsmasq)
+* [Arch wiki](https://wiki.archlinux.org/index.php/dnsmasq)
+
+dnsmasq solves the problem of accessing self hosted stuff when you are inside
+your network. As asking googles DNS for `blabla.org` will return your
+very own public IP and most routers/firewalls wont allow this loopback,
+where your requests should go out and then right back.</br>
+Usual quick way to solve this issue is editing the `hosts` file on your machine,
+but if more devices should "just work" it is a no-go.</br>
+So the answer is running a DNS server that pairs the local machines IP with 
+the correct hostnames, and a DHCP server that tells the devices on the network
+to use this DNS.
 
 # Files and directory structure
 
@@ -26,7 +36,8 @@ Lightweight DHCP and DNS server.
 * `hosts` - a file that can provide additional hostname-ip mapping
 
 `hosts` and `resolve.conf` are just normal system files always in use on any linux
-system.
+system.</br>
+`dnsmasq.conf` comes with the dnsmasq installation.
 
 # Installation
 
@@ -67,23 +78,33 @@ address=/plex.blabla.org/192.168.1.3
 
 # DHCP -------------------------------------------------------------------------
 
-dhcp-range=192.168.1.51,192.168.1.199,255.255.255.0,480h
-# gateway
-dhcp-option=3,192.168.1.1
-
 dhcp-authoritative
+dhcp-range=192.168.1.50,192.168.1.200,255.255.255.0,480h
+# gateway
+dhcp-option=option:router,192.168.1.1
+
+# DHCP static IPs --------------------------------------------------------------
+# mac address : ip address
+
+dhcp-host=08:00:27:68:f9:bf,192.168.1.150
 
 #dhcp-leasefile=/var/lib/misc/dnsmasq.leases
 ```
 
+*extra info*
+
+* `dnsmasq --test` - validates the config
+* `dnsmasq --help dhcp` - lists all the DHCP options
+
 # resolv.conf
 
-Contains DNS nameservers to be used by this linux machine.</br>
+A file that contains DNS nameservers to be used by the linux machine,
+specifically its glibc resolver library.</br>
 Since dnsmasq, a DNS server, is running right on this machine,
-the entries should point to localhost.
+the entries should just point to localhost.
 
-Bit of an issue is that this file is often changed by various system services,
-like systemd or dhcpcd.
+Bit of an issue is that this file is often managed by various system services,
+like dhcpcd, systemd, networkmanager... and they change it as they see fit.</br>
 To prevent this, `resolv.conf` will be flagged as immutable,
 which prevents all possible changes to it unless the attribute is removed.
 
@@ -115,8 +136,10 @@ add immutability, and check.
 
 # /etc/hosts
 
-dnsmasq reads `/etc/hosts` for IP hostname pairs entries.
-This is where you can add hostnames you wish to route to any ip you want.
+This is a file present on every system, linux, windows, mac, android,... 
+where you can assign a hostname to an IP.</br>
+dnsmasq reads `/etc/hosts` for IP hostname pairs and adds them to its own
+resolve records.
 
 Unfortunately no wildcard support.
 But as seen in the `dnsmasq.conf` there is a wildcard section solving this,
@@ -136,16 +159,16 @@ so blabla stuff here is just for show.
 
 # Start the service
 
-Make sure you disable other DHCP servers on the network beforehand,
-usually a router is running one.
-
 `sudo systemctl enable --now dnsmasq`
 
+*Make sure you disable other DHCP servers on the network,
+usually a router is running one.*
+
 # Test it
 
 #### DHCP
 
-Set some machine to use DHCP for its network setting.</br>
+Set some machine on the network to use DHCP for its network setting.</br>
 It should just work. 
 
 You can check on the dnsmasq host, file `/var/lib/misc/dnsmasq.leases`
@@ -177,4 +200,4 @@ which contains the config files.
 
 #### restore
 
-Replace the config files with the one from backup
+Replace the content of the config files with the one from the backup.