Documentation Networking Beat

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Network Device Naming

Servers often have multiple Ethernet ports, either embedded on the motherboard, or on add-in PCI cards. Linux has traditionally named these ports ethX, but there has been no correlation of the ethX names to the chassis labels - the ethX names are non-deterministic. Starting in Fedora 15, Ethernet ports will have a new naming scheme corresponding to physical locations, rather than ethX. Ethernet ports embedded on server motherboards will be named em<port_number>, while ports on PCI cards will be named pci<slot_number>p<port_number>, corresponding to the chassis labels. Additionally, if the network device is an SR-IOV Virtual Function or has Network Partitioning (NPAR) capability, the name will have a suffix of _<virtual_function> or _<partition>.

By changing the naming convention, system administrators will no longer have to guess at the ethX to physical port mapping, or invoke workarounds on each system to rename them into some "sane" order.

This feature affects all physical systems that expose network port naming information in SMBIOS 2.6 or later (specifically field types 9 and 41). Dell PowerEdge 10G and newer servers (PowerEdge 1950 III family, PowerEdge R710 family, and newer), and HP ProLiant G6 servers and newer are known to expose this information, as do some newer desktop models. Furthermore, most older systems expose some information in the PCI IRQ Routing Table, which will be consulted if information is not provided by SMBIOS.

Fedora running as a guest virtual machine will continue to use the ethX names.

Existing installations upgraded to Fedora 15 will not see a change in names unless /etc/udev/rules.d/70-persistent-net.rules is deleted and the HWADDR lines are removed from all /etc/sysconfig/network-scripts/ifcfg-* files, and those files are renamed to use the new device names.

You may continue to write rules in /etc/udev/rules.d/70-persistent-net.rules to change the device names to anything you wish. Such will take precedence over this physical location naming scheme. Such rules may look like:

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:11:22:33:44:55", ATTR{type}=="1", KERNEL=="eth*", NAME="public"

This feature may be disabled by passing "biosdevname=0" on the kernel command line, in which case, behavior will revert to using ethX names.

VPN default visibility

By default, a new network connection using NetworkManager in GNOME 3 has the Available to all users option enabled. This default selection includes new VPN connections. This allows a laptop user to restart the session without having to select the VPN and enter credentials again. However, it may not be desirable to some users. To remove this option, turn off the Available to all users checkbox when setting up the network.

To change the option after a connection has already been created, select the NetworkManager icon in the top-bar, and select Network Settings in the network menu. The Network settings window appears. Select the desired connection and then select the Options button. At the bottom of the connection window, turn off the Available to all users checkbox, and select Save... to save the configuration.