Share a wireless connection via ethernet in GNOME 3.14

There are some situations where you want to do the opposite of creating a wireless hotspot and you want to share a wireless connection to an ethernet connection. For example, if you’re at a hotel that offers only WiFi internet access, you could share that connection to an ethernet switch and plug in more devices. Also, you could get online with your wireless connection and create a small NAT network to test a network device without mangling your home network.

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Creating a bridge for virtual machines using systemd-networkd

There are plenty of guides out there for making ethernet bridges in Linux to support virtual machines using built-in network scripts or NetworkManager. I decided to try my hand with creating a bridge using only systemd-networkd and it was surprisingly easy.

First off, you’ll need a version of systemd with networkd support. Fedora 20 and 21 will work just fine. RHEL/CentOS 7 and Arch Linux should also work. Much of the networkd support has been in systemd for quite a while, but if you’re looking for fancier network settings, like bonding, you’ll want at least systemd 216.

Getting our daemons in order

Before we get started, ensure that systemd-networkd will run on a reboot and NetworkManager is disabled. We also need to make a config file director for systemd-networkd if it doesn’t exist already. In addition, let’s enable the caching resolver and make a symlink to systemd’s resolv.conf:

systemctl enable systemd-networkd
systemctl disable NetworkManager
systemctl enable systemd-resolved
ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf
mkdir /etc/systemd/network

Configure the physical network adapter

In my case, the network adapter connected to my external network is enp4s0 but yours will vary. Run ip addr to get a list of your network cards. Let’s create /etc/systemd/network/uplink.network and put the following in it:

[Match]
Name=enp4s0
 
[Network]
Bridge=br0

I’m telling systemd to look for a device called enp4s0 and then add it to a bridge called br0 that we haven’t configured yet. Be sure to change enp4s0 to match your ethernet card.

Make the bridge

We need to tell systemd about our new bridge network device and we also need to specify the IP configuration for it. We start by creating /etc/systemd/network/br0.netdev to specify the device:

[NetDev]
Name=br0
Kind=bridge

This file is fairly self-explanatory. We’re telling systemd that we want a device called br0 that functions as an ethernet bridge. Now create /etc/systemd/network/br0.network to specify the IP configuration for the br0 interface:

[Match]
Name=br0
 
[Network]
DNS=192.168.250.1
Address=192.168.250.33/24
Gateway=192.168.250.1

This file tells systemd that we want to apply a simple static network configuration to br0 with a single IPv4 address. If you want to add additional DNS servers or IPv4/IPv6 addresses, just add more DNS= and Address lines right below the ones you see above. Yes, it’s just that easy.

Let’s do this

Some folks are brave enough to stop NetworkManager and start all of the systemd services here but I prefer to reboot so that everything comes up cleanly. That will also allow you to verify that future reboots will cause the server to come back online with the right configuration. After the reboot, run networkctl and you’ll get something like this (with color):

networkctl screenshot

Here’s what’s in the screenshot:

IDX LINK             TYPE               OPERATIONAL SETUP     
  1 lo               loopback           carrier     unmanaged 
  2 enp2s0           ether              off         unmanaged 
  3 enp3s0           ether              off         unmanaged 
  4 enp4s0           ether              degraded    configured
  5 enp5s0           ether              off         unmanaged 
  6 br0              ether              routable    configured
  7 virbr0           ether              no-carrier  unmanaged 
 
7 links listed.

My ethernet card has four ports and only enp4s0 is in use. It has a degraded status because there is no IP address assigned to enp4s0. You can ignore that for now but it would be nice to see this made more clear in a future systemd release.

Look at br0 and you’ll notice that it’s configured and routable. That’s the best status you can get for an interface. You’ll also see that my other ethernet devices are in the unmanaged state. I could easily add more .network files to /etc/systemd/network to configure those interfaces later.

Further reading

As usual, the Arch Linux wiki page on systemd-networkd is a phenomenal resource. There’s a detailed overview of all of the available systemd-networkd configuration file options over at systemd’s documentation site.

Test Fedora 22 at Rackspace with Ansible

Fedora Infinity LogoFedora 22 will be arriving soon and it’s easy to test on Rackspace’s cloud with my Ansible playbook:

As with the previous playbook I created for Fedora 21, this playbook will ensure your Fedora 21 instance is fully up to date and then perform the upgrade to Fedora 22.

WARNING: It’s best to use this playbook against a non-production system. Fedora 22 is an alpha release at the time of this post’s writing.

This playbook should work well against other servers and virtual machines from other providers but there are a few things that are Rackspace-specific cleanups that might not apply to other servers.

Xerox ColorQube 9302 and Linux

I do a bunch of Linux-related tasks daily. Some are difficult and others are easy. Printing has always been my nemesis.

Some printers offer up highly standardized methods for printing. For example, many HP printers simply work with JetDirect and PCL 5. However, the quirkier ones that require plenty of transformations before paper starts rolling can be tricky.

We have some Xerox ColorQube printers at the office and they require some proprietary software to get them printing under Linux. To get started, you’ll need a Linux printer driver for the Xerox ColorQube 9200 series.

Once you’ve downloaded the RPM (or DEB), install it:

sudo rpm -Uvh Xeroxv5Pkg-Linuxx86_64-5.15.551.3277.rpm

Start the Xerox Printer Manager:

sudo xeroxprtmgr

You should have a screen like this:
Xerox Printer Manager_006

Press the double down arrow button at the top (it’s the one on the left), and then press the button at the top right of the next window that looks like rectangles stacked on top of one another. Choose Manual Install from the menu that appears.

Selection_008

In the next menu, enter a nickname for the printer, the printer’s IP address, and select the correct printer model from the list. The printer should be properly configured in your CUPS system afterwards:

Printers_009

Any new print jobs set to the printer will cause the Xerox printer manager to pop up. This gives you the opportunity to customize your job (collating, stapling, etc) and you can also use secure print (which I highly recommend).