2016-12-30 linux

Simple Networking in Arch Linux

Arch Linux is my favorite. I've been running Arch for a year now and though I've had many ups and downs, the ups always outweigh the downs. Nowadays, I can only imagine running Arch or an operating system with extremely similar design philosophies. However, I've always had one major problem with Arch Linux: networking.

I am not a networking guru. I enjoyed my Computer Networks course and I am slightly fond of web development, but when it comes to connecting to the Internet in Arch Linux, it's always a struggle. A big struggle. But after a year of tinkering around, I finally no longer boot into my dual partition of Ubuntu when networking gets hard.

So, you go to an airport, or a Starbucks, or a friend's house and you need to connect to a new network? Well, below is the recipe for simple networking in Arch Linux:

Before You Leave Home

  1. Switch to systemd-networkd
    This is the major step, especially if you are using NetworkManager, and you should do this when you set up your fresh install of Arch Linux, preferably. If you didn't, then stay home and make the switch before you brave the world of new networks. Here is a simple guide.

  2. Set up WPA Supplicant
    Install the wpa_supplicant package from the official Arch repositories. Then, you will need to set up the configuration files. The minimal config file should set your control interface. The advanced config file can set your networks and passwords. You should first find your wireless interface name with ip link, and name your file wpa_supplicant-interface.conf in etc/wpa_supplicant/. A basic version of my config file is shown below.

    # /etc/wpa_supplicant/wpa_supplicant-wlp3s0.conf  
    eapol_version=1     # this is the default  
    ap_scan=1           # also the default  
    fast_reauth=1       # also the default  
    p2p_disabled=1      # through many trials & errors, this has served me well  
    # an example network configuration, but not what this post is about  
        ssid="Google Starbucks"  

When You're Ready to Network

  1. Start the WPA commandline client
    Type sudo wpa_cli from your terminal. Root privileges required. You should get a nice description of the version of wpa_cli you are using, as well as the selected interface, which should be the same interface as the one you created a configuration file for.

  2. Scan for available networks
    Type scan, and wait until the client says something along the lines of CTRL-EVENT-SCAN-RESULTS. This means the scan has finished and you can now see the available networks in your range.

  3. List available networks
    Type scan_results. You should get a list of the found networks in return. Take note of the SSID of the network you want to connect to (the last column's value). Let's assume your chosen network's SSID is example network.

  4. Add a network
    Type add_network from the commandline. You should recieve a number in response. Let's assume for the sake of this post that the number is 2. Now you're ready to connect.

  5. Set the network identification and passphrase
    Assuming network 2 and SSID example_network, type set_network 2 ssid "example network". You should get an OK in return. Else, you can't connect to this network or you misspelled the name. Then, set the passphrase in a similar manner: set_network 2 psk "sup3r_s3cr3t_p4ssphr4s3". Once again, you should get an OK in return.

  6. Enable the network!
    The tricky step for me. I was unaware I had to select and enable the network I wanted. Well, it's easy. To be safe, first enable your network: enable_network 2. Then, select it: select_network 2. This last command should disable all other networks, but I like to play it safe by enabling the new network first.

That's it. You should get authenticating and key negotiation messages, and then you're set. Super simple, right? Why did it take me so long to figure this out? Great question.