Ubuntu networking
IP configuration
Temporary set IP address
sudo ifconfig eth0 192.168.100.2/24 up sudo ifconfig eth0 192.168.100.2 netmask 255.255.255.0
Temporary add default GW
sudo route add default gw 192.168.100.1 eth0
Verify your default gateway configuration
route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.100.1 0.0.0.0 UG 0 0 0 eth0 192.168.100.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
DNS for your temporary network configuration, you can add DNS server IP addresses in the file /etc/resolv.conf. Please bear in mind these changes will be overwritten.
echo "nameserver 8.8.8.8" >> /etc/resolv.conf nameserver 8.8.8.8 nameserver 8.8.4.4
If you no longer need this configuration and wish to purge all IP configuration from an interface, you can use the ip command with the flush option as shown below:
ip addr flush eth0
Networking configuration file - Debian based distros
Permanent changes to IP address are saved in /etc/network/interfaces
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.100.2
netmask 255.255.255.0
network 192.168.100.0
broadcast 192.168.100.255
gateway 192.168.100.1
dns-nameservers 192.168.100.1 8.8.8.8
dns-domain acme.com #optional
dns-search acme.com #adds search entry to /etc/resolv.conf
Options on ethernet interfaces:
- inet static - Defines a static ip address.
- inet manual - Does not define an ip address to a interface. Generally used by interfaces that are bridge or aggregation members, or have a vlan device configured on it.
- inet dhcp - Acquire ip through dhcp protocol.
- inet6 static - Defines a static ipv6 address.
Resolvconf
Switch to resolvconf for /etc/resolv.conf management in Ubuntu 12.04. This is the result of the implementation of: foundations-p-dns-resolving
resolvconf is a set of script and hooks managing DNS resolution. The most notable difference for the user is that any change manually done to /etc/resolv.conf will be lost as it gets overwritten next time something triggers resolvconf. Instead, resolvconf uses DHCP client hooks, a Network Manager plugin and /etc/network/interfaces to generate a list of nameservers and domain to put in /etc/resolv.conf.
Resolvconf has a /etc/resolvconf/resolv.conf.d/ directory that can contain base, head, original and tail files. All in resolv.conf format.
- base: Used when no other data can be found
- head: Used for the header of resolv.conf, can be used to ensure a DNS server is always the first one in the list
- original: Just a backup of your resolv.conf at the time of resolvconf installation
- tail: Any entry in tail is appended at the end of the resulting resolv.conf. In some cases, upgrading from a previous Ubuntu release, will make tail a symlink to original (when we think you manually modified resolv.conf in the past)
Add nameservers, search path etc outside of your dhcp assignments
$ sudo vi /etc/resolvconf/resolv.conf.d/base #add below: nameserver 192.168.1.254 search home.local $ sudo resolvconf -u #update resolv.conf
Wireless from command line
Manual configuration from the command-line
- 3 steps for WEP
sudo iwconfig eth[N] essid [SSID] sudo iwconfig eth[N] key restricted s:[PASSWORD] sudo dhclient
- WPA is more complicated
sudo mkdir /etc/wpa_supplicant
cd /etc/wpa_supplicant
sudo echo network = { > wpa_supplicant.conf
sudo echo ssid="SSID" >> wpa_supplicant.conf
sudo echo key_mgmt=WPA-PSK >> wpa_supplicant.conf
sudo echo psk="PRESHAREDKEY" >> wpa_supplicant.conf
sudo echo } >> wpa_supplicant.conf
wpa_supplicant -D wext -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf #associate the client with the ssid described in 'wpa_supplicant.conf' file
# -D driver, -i interface, -c configuration file
#use driver wext Linux wireless extensions (generic) for Dell 620/630,
sudo dhclient wlan0 #to obtain IP address via dhcp
sudo vi /etc/network/interfaces #add the network permanently
Now add after "auto eth[N] ..." & "iface eth[N] .." :
wpa-driver wext #driver for network card, this can be obtained by command 'wpa_supplicant --help | grep -A 5 drivers:' wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
Save the file and restart networking sudo service networking restart
- Example of /etc/network/interfaces part for a wireless WPA-PSK configuration
auto wlan0 auto wlan0
iface wlan0 inet dhcp iface wlan0 inet static
wpa-driver wext wpa-driver wext
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
address 192.168.100.2
netmask 255.255.255.0
network 192.168.100.0
broadcast 192.168.100.255
gateway 192.168.100.1
dns-nameservers 192.168.100.1 8.8.8.8
Networking Tools
nm-tool - utility to report NetworkManager state and devices, it provides information about NM, device and wireless networks.
Remove Network Manager
Tested on Ubuntu 15.10
sudo service network-manager stop sudo apt-get remove --purge network-manager network-manager-gnome network-manager-pptp network-manager-pptp-gnome ps aux | grep etwork #this shows if NM brought the network up sudo service networking restart #at this point you may still have some processes calling NetworkManager DHCPclient configuration running sudo reboot
- Be careful - this may remove udev scripts that generate the interface names dynamically
Error: lost self generated ethX interface name
$ ip addr | grep -A1 ^2 #grep lines starting with '2' including -A1 one line after 2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:0c:29:63:6d:19 brd ff:ff:ff:ff:ff:ff
There is missing udev file
/etc/udev/rules.d/70-persistent-net.rules
Solution (not confirmed, not worked
sudo sudo service udev status #check if the service is healthy sudo apt-get install udev udev-discover sudo udevadm trigger --type=devices --action=change sudo udevadm control --reload-rules sudo /lib/udev/write_net_rules all_interfaces sudo /lib/udev/rules.d/75-persistent-net-generator-rules
Ethernet Interfaces
- Identify Ethernet Interfaces, output from Dell D620
lshw shows here an interface with the logical name of eth0 along with bus information, driver details and all supported capabilities
sudo lshw -class network
*-network
description: Ethernet interface
product: BCM4401-B0 100Base-TX
vendor: Broadcom Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: eth0
version: 02
serial: 00:15:c5:4a:16:5a
size: 10MB/s
capacity: 100MB/s
width: 32 bits
clock: 33MHz
capabilities: (snipped for brevity)
configuration: (snipped for brevity)
resources: irq:17 memory:ef9fe000-ef9fffff
- Ethernet Interface Logical Names
Interface logical names are configured in the file /etc/udev/rules.d/70-persistent-net.rules. If you would like control which interface receives a particular logical name, find the line matching the interfaces physical MAC address and modify the value of NAME=ethX to the desired logical name. Reboot the system to commit your changes.
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:15:c5:4a:16:5a", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:15:c5:4a:16:5b", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"
- Ethernet Interface Settings
ethtool is a program that displays and changes Ethernet card settings such as auto-negotiation, port speed, duplex mode, and Wake-on-LAN. It is not installed by default, but is available for installation in the repositories.
sudo apt-get install ethtool
The following is an example of how to view supported features and configured settings of an Ethernet interface.
sudo ethtool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: g
Wake-on: d
Current message level: 0x000000ff (255)
Link detected: yes
Changes made with the ethtool command are temporary and will be lost after a reboot. If you would like to retain settings, simply add the desired ethtool command to a pre-up statement in the interface configuration file /etc/network/interfaces.
The following is an example of how the interface identified as eth0 could be permanently configured with a port speed of 1000Mb/s running in full duplex mode.
auto eth0 iface eth0 inet static pre-up /usr/sbin/ethtool -s eth0 speed 1000 duplex full
Change the logical name for an interface
[not confirmed that working on Ubunu or Red Hat]
say you have two nics installed on the system, eth0, and eth1. At some times latter, you removed eth0 from the system. Now eth1 is the only nic in your machine... and you want to rename this nic(eth1) as eth0.
rcnetwork stop vi /etc/udev/rules.d/30-net_persistent_names.rules
here you find a line as
SUBSYSTEM=="net", ACTION=="add", SYSFS{address}=="00:02:b3:22:84:f3", IMPORT="/lib/udev/rename_netiface %k eth1"
simply change eth1, as eth0,
SUBSYSTEM=="net", ACTION=="add", SYSFS{address}=="00:02:b3:22:84:f3", IMPORT="/lib/udev/rename_netiface %k eth0"
save and exit
Now execute the following command
/lib/udev/rename_netiface <old> <new> i.e /lib/udev/rename_netiface eth1 eth0 rcnetwork start
even we can give any valid name to our nic, say e.g we want to name our eth0 as lan0, then
rcnetwork stop vi /etc/udev/rules.d/30-net_persistent_names.rules
here you find a line as
SUBSYSTEM=="net", ACTION=="add", SYSFS{address}=="00:02:b3:22:84:f3", IMPORT="/lib/udev/rename_netiface %k eth0"
simply change eth1, as lan0,
SUBSYSTEM=="net", ACTION=="add", SYSFS{address}=="00:02:b3:22:84:f3", IMPORT="/lib/udev/rename_netiface %k lan0"
Now execute the following command
/lib/udev/rename_netiface eth0 lan0
NOTE: say we gave our nic a name as lanX, nicX, or intX(i.e non ethX name), and then want to change the name from lan0 to eth0, all the above steps are required, and reboot too.
Links and references
- Ubuntu 10.04 network-configuration Wiki the most used here
- Ubuntu_Precise_Network_Management