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Iproute2

lastmod 2026-01-05created 2020-07-2319 edits

(For the OSI network layer protocol, see Internet Protocol.)

iproute2 is a collection of userspace utilities for controlling and monitoring various aspects of networking in the Linux kernel, including routing, network interfaces, tunnels, traffic control, and network-related device drivers.

iproute2 is an open-source project released under the terms of version 2 of the GNU General Public License. Its development is closely tied to the development of networking components of the Linux kernel. As of December 2013, iproute2 is maintained by Stephen Hemminger. The original author, Alexey Kuznetsov, was responsible for the quality of service (QoS) implementation in the Linux kernel.

iproute2 collection contains the following command-line utilities: ip, ss, bridge, rtacct, rtmon, tc, ctstat, lnstat, nstat, routef, routel, rtstat, tipc, arpd and devlink. tc is used for traffic control. iproute2 utilities communicate with the Linux kernel using the netlink protocol. Some of the iproute2 utilities are often recommended over now-obsolete net-tools utilities that provide the same functionality. Below is a table of obsolete utilities and their iproute2 replacements.

Categories

ip (linux command)

See Iproute2:ip for details.

How to check whether a network interface is physically connected

Run the ip link command; if state DOWN next to the interface status information changes to state UP, it is connected. 

$ ip link
...
2: wlp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DORMANT group default qlen 1000
...

Installing The Linux Dummy-Network Interface

If your NST system does not have an active NIC adapter installed or is off-line from the network, you can install a Dummy Network Interface Module to simulate a network computing environment. This can be quite useful for testing out various networking tools (e.g., Wireshark and Snort) with the Network Security Toolkit when off-line. Use the following procedure to install the Linux Dummy-Network Interface:

1. Add an IP address and host name to your "/etc/hosts" table. For example, an Internet address of 10.0.0.1 would result in: 

$ echo 10.0.0.1 ${HOSTNAME} >> /etc/hosts;

2. Preload the dummy network driver on the machine. If this command is successful, you do not receive any messages from the server. 

$ modprobe dummy;

3. Create the interface(s) (Example: Network Interface: dummy1): 

$ ip link add dummy1 type dummy;

4. Bind an IPv4 Address to Network Interface dummy1: 

$ ip addr add 10.0.0.1/24 dev dummy1;

## OR:
$ ip addr add ${HOSTNAME}/24 dev dummy1;

5. Bring the dummy1 Network Interface up: 

$ ip link set dummy1 up;

6. If you need to add more than one (1) dummy interface use the following: 

$ ip link add dummy2 type dummy;
$ ip link add dummy3 type dummy;
$ ip addr add 10.0.0.2/24 dev dummy2;
$ ip addr add 10.0.0.3/24 dev dummy3;
$ ip link set dummy2 up; 
$ ip link set dummy3 up;

7. Check the network bindings with the linux ip command: 

 [root@nst28-dev ~]# ip a
 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
        valid_lft forever preferred_lft forever
     inet6 ::1/128 scope host 
        valid_lft forever preferred_lft forever
 2: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 36:f5:1b:3a:12:41 brd ff:ff:ff:ff:ff:ff
     inet 10.0.0.1/24 scope global dummy1
        valid_lft forever preferred_lft forever
     inet6 fe80::34f5:1bff:fe3a:1241/64 scope link 
        valid_lft forever preferred_lft forever
 3: dummy2: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 6a:5c:3f:56:dc:2d brd ff:ff:ff:ff:ff:ff
     inet 10.0.0.2/24 scope global dummy2
        valid_lft forever preferred_lft forever
     inet6 fe80::685c:3fff:fe56:dc2d/64 scope link 
        valid_lft forever preferred_lft forever
 4: dummy3: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 86:d5:9f:08:f1:32 brd ff:ff:ff:ff:ff:ff
     inet 10.0.0.3/24 scope global dummy3
        valid_lft forever preferred_lft forever
     inet6 fe80::84d5:9fff:fe08:f132/64 scope link 
        valid_lft forever preferred_lft forever

Removing The Linux Dummy-Network Interface

1. Unbind the dummy established Network Interface(s): 

$ ifconfig dummy1 down;
$ ifconfig dummy2 down;
$ ifconfig dummy3 down;

2. Remove interface: 

$ ip link delete dummy1
$ ip link delete dummy2
$ ip link delete dummy3

3. Remove the dummy kernel module. 

$ rmmod dummy;

Edit Routing Table

Add Route 

$ sudo ip route add 10.0.3.0/24 via 10.0.3.1

How to check the IP address of a specific interface

Script to check the IPv4 address of the "nebula1" interface: 

ip -4 addr show nebula1 | grep -oP '(?<=inet\s)\d+(\.\d+){3}'

How to configure communication between IPs in different ranges

See Internet Protocol#How to configure communication between IPs in different ranges.

Examples

Add the following examples:

  • List all network interfaces details
  • Assign an IP address
  • Delete the IP address
  • Flush the IP address
  • Mark interface as UP or DOWN
  • Set the txqueuelen
  • Set the MTU
  • Show ARP cache
  • Add a new ARP entry
  • Delete a ARP entry
  • Flush ARP cache
  • Show routing table
  • Add a new route
  • Delete a route
  • Change MAC address
  • Configure color output
  • Displaying all IP address
  • Old vs. new tool

See also

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