[Linux] Journal.

I have three network possibilities at boot time: ethernet, wireless at work & wireless at home. Here’s my setup to detect and bring up the right configuration.

First we try to detect if ethernet is connected before we bring up the interface. We use mii-tool to give us the link status of an interface. If [...]

Dnsmasq as a lightweight DNS proxy and a DHCP server I use for my home network. apt-get install dnsmasq.

On my server eth0 is connect to my ADSL modem and gets dhcp from my ISP. eth1 is connected to the wireless access point which our laptops connects to, so we need to configure dnsmasq to listen [...]

Setup the following firewall policy for my server:

$ iptables -P INPUT DROP

Default drop everything.

$ iptables -A INPUT -i eth1 -j ACCEPT
$ iptables -A INPUT -i lo -j ACCEPT

Accept everything on local network (eth1 connects to home access point) and local interface.

$ iptables -A INPUT -i eth0 -p tcp -m multiport –dports 22,80 -j ACCEPT

Offer ssh [...]

My wireless interface have many profiles, some profiles run as dhcp client while others run as dhcp server. This means I have to setup my dhcp server (I use dnsmasq) to listen on the interface when the profile that acts as dhcp server is brought up, and remove that interface when the profile is brought [...]

Here’s a great link on network configuration.

My officemates and I finally signed up with dynamic DNS to point to our local network addresses so we can exchange files without asking for each other’s IP all the times.

They signed up with DynDNS for an account and I used my existing account with No-IP to add an additional host for my laptop.

To set [...]