Ubuntu Network Restart

Starting Ubuntu 14.04, you no longer can bounce the network using the following command:

sudo /etc/init.d/networking restart
sudo service networking restart

But, I managed to do this:

sudo ifdown eth0
sudo ifup eth0

Gigabit DSL called G.fast

There’s a new broadband standard called G.fast with speeds up to 1Gbps over regular copper wires without the need for a fiber backbone. G.fast is scheduled to be approved by 2014. G.fast users should be able to install it without assistance. The self-installing system will eliminate costs for providers that they would have to pay for technicians. This could significantly improve the speed of the rollout. G.fast is meant to support bandwidth-intensive applications. Initial tests resulted 1.1Gbps over 70 meters and 800Mbps over 100 meters over a single cable. Consumers should expect G.fast connections to be available in 2015.

Use Nmap To Scan Your Network

The Nmap utility will scan devices connected to your network. Nmap is a free open-source utility used by network admins and anyone to explore, scan, secure and audit the network. For example, if your internal network is 10.10.10.0/24 network, you can use the following Nmap options to scan your network.

nmap -sP 10.10.10.0/24

The command above produces the following output:

As you can see, the nmap utility has found 8 devices connected to my network. It usually takes 30 seconds or so to scan the entire network. With the available data, I can now ping, ssh, or view the device via web browser if that service is available. Nmap makes troubleshooting the network that much more easier.

Just like most Linux utilities, nmap has a ton of options worth checking. Simply type -- help to read more options.

nmap --help

If you are a Windows user, the nmap utility is available for download.

For Ubuntu users, simply type the following to install

sudo apt-get install nmap

Double NAT

I redesigned my home network the other day. Previously, I had two separate private networks. One wired network and a wireless network. Both networks were behind a Smoothwall Linux firewall running on my old PC. The wired network was directly behind the Smoothwall firewall while the wireless network was behind the wired network which means it’s going through two NATs or network address translations. Well, it’s not a very good design. It was probably causing a little bit of propagation delay.

Continue reading “Double NAT”