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Devices

  • ethX: Ethernet devices.
  • wlanX: Wireless devices.
  • brX: Bridge interfaces
  • vmnetZ: virtual devices

Configuring and Controlling Devices​

ip utility is used to configure, control and query interface parameters and routing. It replaced the ifconfig as it's faster and more versatile. Settings changed using ip are not persistent.

Format:

ip [options] object {command | help}

# for reading commands from file
ip [-force] -batch /path/to/file

Popular object:

  • address: ipv4/6 protocol device address.
  • link: network devices
  • maddress: multicast address
  • monitor: watch for netlink messages
  • route: routing table entry
  • rule: rule in routing policy db
  • tunnel: tunnel over ip

Examples:

# show info for all interfaces
ip link show

# show stats (rx/tx) about eth0 
ip -s link show eth0 
# OR
cat /proc/net/dev

# set ip address
sudo ip addr add 192.168.1.7 dev eth0

# take down interface
sudo ip link set eth0 down

# set mtu to 1480 bytes
sudo ip link set eth0 mtu 1480

# set networking route
sudo ip route add 172.16.1.0/24 via 192.168.1.5

The device configuration, information and statistics are held in the following filesystem locations:

less /proc/net/dev

head -n 4 /proc/net/dev
Inter-|   Receive                                                |  Transmit
 face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
califf0535d9c94: 98940135  518876    0    0    0     0          0         0 60376340  463276    0    0    0     0       0          0
calie8c5a45cbcd: 2673411   33886    0    0    0     0          0         0  2801482   20678    0    0    0     0       0          0

Device configuration and statistics can be found in:

cat /sys/class/net/docker0/statistics/rx_missed_errors
0

Each distro has it's own set of files that include persistent network device configuration (NIC).

  • RedHat:
    • /etc/sysconfig/network
    • /etc/sysconfig/network-scripts/ifcfg-ethX
    • /etc/sysconfig/network-scripts/ifcfg-ethX:Y
    • /etc/sysconfig/network-scripts/route-ethX
  • Debian:
    • /etc/network/interfaces
  • SUSE:
    • /etc/sysconfig/network

Network Manager​

The preferred/modern method to interact with network devices is using the Network Manager.

We can change the network configuration using nmcli.

Installation and enablement:

sudo apt install network-manager
sudo /etc/init.d/network-manager start
# contains many useful examples
man nmcli-examples 

# see list of wifi APs
nmcli device wifi list