{"id":7612,"date":"2020-09-18T21:11:00","date_gmt":"2020-09-18T19:11:00","guid":{"rendered":"https:\/\/monodes.com\/predaelli\/?p=7612"},"modified":"2020-09-18T17:11:43","modified_gmt":"2020-09-18T15:11:43","slug":"internet-connection-sharing-with-networkmanager-fedora-magazine","status":"publish","type":"post","link":"https:\/\/monodes.com\/predaelli\/2020\/09\/18\/internet-connection-sharing-with-networkmanager-fedora-magazine\/","title":{"rendered":"Internet connection sharing with NetworkManager – Fedora Magazine"},"content":{"rendered":"

Internet connection sharing with NetworkManager – Fedora Magazine<\/a><\/em><\/p>\n

Or nmtui<\/code>, nmcli<\/code> and other commands for the shell wizard<\/p>\n

<\/p>\n

\n

Internet connection sharing with NetworkManager<\/h1>\n
Posted<\/span> by Beniamino Galvani<\/a> <\/span> on June 17, 2020<\/a><\/span><\/div>\n
\n

NetworkManager is the network configuration daemon used on Fedora and many other distributions. It provides a consistent way to configure network interfaces and other network-related aspects on a Linux machine. Among many other features, it provides a Internet connection sharing functionality that can be very useful in different situations.<\/p>\n

F<\/mark>or example, suppose you are in a place without Wi-Fi and want to share your laptop\u2019s mobile data connection with friends. Or maybe you have a laptop with broken Wi-Fi and want to connect it via Ethernet cable to another laptop; in this way the first laptop become able to reach the Internet and maybe download new Wi-Fi drivers.<\/p>\n

In cases like these it is useful to share Internet connectivity with other devices. On smartphones this feature is called \u201cTethering\u201d and allows sharing a cellular connection via Wi-Fi, Bluetooth or a USB cable.<\/p>\n

This article shows how the connection sharing mode offered by NetworkManager can be set up easily; it addition, it explains how to configure some more advanced features for power users.<\/p>\n

<\/span><\/p>\n

How connection sharing works<\/h2>\n

The basic idea behind connection sharing is that there is an upstream<\/em> interface with Internet access and a downstream<\/em> interface that needs connectivity. These interfaces can be of a different type\u2014for example, Wi-Fi and Ethernet.<\/p>\n

If the upstream interface is connected to a LAN, it is possible to configure our computer to act as a bridge<\/em>; a bridge is the software version of an Ethernet switch. In this way, you \u201cextend\u201d the LAN to the downstream network. However this solution doesn\u2019t always play well with all interface types; moreover, it works only if the upstream network uses private addresses.<\/p>\n

A more general approach consists in assigning a private IPv4 subnet to the downstream network and turning on routing between the two interfaces. In this case, NAT (Network Address Translation) is also necessary. The purpose of NAT is to modify the source of packets coming from the downstream network so that they look as if they originate from your computer.<\/p>\n

It would be inconvenient to configure manually all the devices in the downstream network. Therefore, you need a DHCP server to assign addresses automatically and configure hosts to route all traffic through your computer. In addition, in case the sharing happens through Wi-Fi, the wireless network adapter must be configured as an access point.<\/p>\n

There are many tutorials out there explaining how to achieve this, with different degrees of difficulty. NetworkManager hides all this complexity and provides a shared<\/em> mode that makes this configuration quick and convenient.<\/p>\n

Configuring connection sharing<\/h2>\n

The configuration paradigm of NetworkManager is based on the concept of connection (or connection profile). A connection is a group of settings to apply on a network interface.<\/p>\n

This article shows how to create and modify such connections using nmcli<\/em>, the NetworkManager command line utility, and the GTK connection editor. If you prefer, other tools are available such as nmtui<\/em> (a text-based user interface), GNOME control center or the KDE network applet.<\/p>\n

A reasonable prerequisite to share Internet access is to have it available in the first place; this implies that there is already a NetworkManager connection active. If you are reading this, you probably already have a working Internet connection. If not, see this article<\/a> for a more comprehensive introduction to NetworkManager.<\/p>\n

The rest of this article assumes you already have a Wi-Fi connection profile configured and that connectivity must be shared over an Ethernet interface enp1s0<\/em>.<\/p>\n

To enable sharing, create a connection for interface enp1s0 and set the ipv4.method property to shared <\/em>instead of the usual auto<\/em>:<\/p>\n

$ nmcli connection add type ethernet ifname enp1s0 ipv4.method shared con-name local<\/pre>\n
The shared IPv4 method does multiple things:<\/p>\n