# Using the Linux IP Command to Manage Server Network Interfaces The `ip` command is a built-in Linux network management utility that offers a wide range of features and tools for managing network interfaces. It's an improved utility that combines the functionality of legacy commands such as `ifconfig`, `arp`, and `route` into a single tool for managing, monitoring, and troubleshooting your server's network interfaces. This guide covers using the `ip` command to manage `ip` objects such as links, addresses, routes, and neighbors, including interface configuration, static routing, enabling/disabling interfaces, and MTU management. By the end, you'll be able to inspect, configure, and troubleshoot your server's network interfaces using the `ip` command, following Linux network interface management practices documented in [**Vultr Docs**](https://docs.vultr.com/how-to-use-the-linux-ip-command-to-manage-server-network-interfaces). --- ## Prerequisites Before you begin, you need to: - Deploy an Ubuntu 24.04 server instance to test the `ip` command functionalities. - Attach the server to a VPC network. - Access the server using SSH as a non-root user with sudo privileges. ## How to Use the IP Command The `ip` command uses the following syntax to manage network information and interfaces on your server. ```console ip [OPTIONS] OBJECT COMMAND [ARGUMENTS] ``` Within the above command: - **OPTIONS**: Sets the `ip` command operation mode. - **OBJECT**: Specifies the type of network object to view or manage. For example, `link`, `address`, `route`. - **COMMAND**: Defines the action to perform on the specified object. For example, `add`, `del`, `show`. - **ARGUMENTS**: Sets additional options to execute with the command. ## View Network Interface Information The `ip` command displays network interface information at varying levels of detail depending on the object and options used. **1\. View information about all network interfaces available on the server:** ```console ip link show ``` Your output should be similar to the one below. ```plaintext 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: enp1s0: mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 56:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff 3: enp8s0: mtu 1450 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` Based on the above output, the command displays the total number of available interfaces, the MTU value, state, and MAC address for each interface. Active interfaces use the `UP` state while inactive interfaces use the `DOWN` state. Interfaces with a `DOWN` state cannot send or receive network traffic on the server unless enabled. **2\. Display network interfaces in an active and running state:** ```console ip link show up ``` Output: ```plaintext 1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: enp1s0: mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 56:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff 3: enp8s0: mtu 1450 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` **3\. Use the** `-br` **option to display only important information about the network interfaces:** ```console ip -br link show ``` Output: ```plaintext lo UNKNOWN 00:00:00:00:00:00 enp1s0 UP 56:00:04:ef:40:23 enp8s0 UP 5a:00:04:ef:40:23 ``` **4\. Use the** `addr` **option, or its** `a` **shorthand, to view full information including IP addresses on all network interfaces:** ```console ip a ``` Your output should look like the one below. ```plaintext 1: lo: 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: enp1s0: mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 56:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff inet 192.0.2.100/23 brd 192.0.2.255 scope global dynamic enp1s0 valid_lft 78163sec preferred_lft 78163sec inet6 2a05:f480:2c00:1ef7:5400:4ff:feef:4023/64 scope global dynamic mngtmpaddr noprefixroute valid_lft 2591891sec preferred_lft 604691sec inet6 fe80::5400:4ff:feef:4023/64 scope link valid_lft forever preferred_lft forever 3: enp8s0: mtu 1450 qdisc mq state UP group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff inet 10.50.112.3/20 brd 10.50.127.255 scope global enp8s0 valid_lft forever preferred_lft forever inet6 fe80::5800:4ff:feef:4023/64 scope link valid_lft forever preferred_lft forever ``` **5\. View specific information about a specific network interface. For example, view information about the VPC interface,** `enp8s0`**:** ```console ip addr show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 1450 qdisc mq state UP group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff inet 10.50.112.3/20 brd 10.50.127.255 scope global enp8s0 valid_lft forever preferred_lft forever inet6 fe80::5800:4ff:feef:4023/64 scope link valid_lft forever preferred_lft forever ``` **6\. View detailed statistics about a specific network interface. For example,** `enp8s0`**:** ```console ip -s link show enp8s0 ``` Your output should be similar to the one below. ```plaintext 3: enp8s0: mtu 1450 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped missed mcast 25426631 61808 0 0 0 0 TX: bytes packets errors dropped carrier collsns 4351567 40677 0 0 0 0 ``` ## Manage Interface IP Addresses Using the IP Command IP addresses can be assigned to network interfaces using the Dynamic Host Configuration Protocol (DHCP) or static addressing to enable network connections on the interface. DHCP is the default address assignment protocol on most servers, but static IP addressing may be required when working with multiple addresses or new interfaces on your server. **1\. Add a new IP address on your network interface. Replace** `enp8s0` **with your desired interface name:** ```console sudo ip addr add 192.168.1.10/24 dev enp8s0 ``` The above command adds a new private network address `192.168.1.10` to the `enp8s0` interface. Depending on your addressing scheme, the interface can run with multiple IP addresses that offer different functions or services on your server. **2\. View the interface information to verify that the new IP address is available:** ```console ip addr show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 1450 qdisc mq state UP group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff inet 10.50.112.3/20 brd 10.50.127.255 scope global enp8s0 valid_lft forever preferred_lft forever inet 192.168.1.10/24 scope global enp8s0 valid_lft forever preferred_lft forever inet6 fe80::5800:4ff:feef:4023/64 scope link valid_lft forever preferred_lft forever ``` When using multiple IP addresses, you may need to configure routing to enable specific network connections to use the interface IP address. **3\. Use the** `del` **option to remove IP addresses on network interfaces. For example, remove the** `192.168.1.10/24` **address on the** `enp8s0` **interface:** ```console sudo ip addr del 192.168.1.10/24 dev enp8s0 ``` **4\. View the interface address information to verify that the address is removed:** ```console ip addr show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 1450 qdisc mq state UP group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff inet 10.50.112.3/20 brd 10.50.127.255 scope global enp8s0 valid_lft forever preferred_lft forever inet6 fe80::5800:4ff:feef:4023/64 scope link valid_lft forever preferred_lft forever ``` ## Configure Static Routing Using the IP Command Static routing directs traffic to remote networks through a specific network interface or IP address as the next hop to reach the network. Network requests to unmatched destinations are directed through the default route via the main server interface, while requests to unknown routes may fail due to missing route information. **1\. View the default IP routing table:** ```console ip route show ``` Your output should be similar to the one below. ```plaintext default via 192.0.2.100 dev enp1s0 proto dhcp src 192.0.2.100 metric 100 10.50.112.0/20 dev enp8s0 proto kernel scope link src 10.50.112.3 192.0.2.0/23 dev enp1s0 proto kernel scope link src 192.0.2.100 169.254.169.254 via 192.0.2.100 dev enp1s0 proto dhcp src 192.0.2.100 metric 100 ``` Based on the above output, direct network addresses use the `dev` option while non-linked addresses use the `via` option to direct network traffic using the specified address as the next hop. The `default` route handles all unknown routes on the server unless specified in the routing table. **2\. Add a new static route to a remote network such as** `10.0.0.0/16` **accessible through a server on the VPC network at** `10.50.112.4` **as the next hop:** ```console sudo ip route add 10.0.0.0/16 via 10.50.112.4 ``` **3\. View the routing table again to verify that the new route is available:** ```console ip route show ``` Output: ```plaintext default via 192.0.2.100 dev enp1s0 proto dhcp src 192.0.2.100 metric 100 10.0.0.0/16 via 10.50.112.4 dev enp8s0 10.50.112.0/20 dev enp8s0 proto kernel scope link src 10.50.112.3 192.0.2.0/23 dev enp1s0 proto kernel scope link src 192.0.2.100 169.254.169.254 via 192.0.2.100 dev enp1s0 proto dhcp src 192.0.2.100 metric 100 ``` ## Enable or Disable Network Interfaces Disabling a network interface stops it from sending or receiving traffic without removing its configuration, which is useful for maintenance or troubleshooting. **1\. Use the** `ip link set` **command to disable the** `enp8s0` **interface:** ```console sudo ip link set dev enp8s0 down ``` **2\. View the network interface status and verify that the state is** `DOWN`**:** ```console ip link show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 1450 qdisc mq state DOWN mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` **3\. Enable the network interface:** ```console sudo ip link set dev enp8s0 up ``` **4\. View the interface information to verify the new status:** ```console ip link show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 1450 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` ## Managing the Network Interface MTU (Maximum Transmission Unit) MTU is the maximum size of a packet in bytes that can be transmitted over a network interface without fragmentation. The default MTU value on most network interfaces is `1500`. Depending on your needs, you may modify the value to allow the transfer of large or small data packets on private networks such as a VPC network. **1\. View your target interface MTU value. For example, the VPC interface** `enp8s0`**:** ```console ip link show enp8s0 ``` **2\. Verify the MTU value in your output, similar to the one below:** ```plaintext 3: enp8s0: mtu 1450 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` **3\. Set a new MTU value on the interface. For example,** `3000`**, to transfer large data packets and improve efficiency with other servers in the VPC network:** ```console sudo ip link set dev enp8s0 mtu 3000 ``` **4\. View the interface information again and verify the new MTU value:** ```console ip link show enp8s0 ``` Output: ```plaintext 3: enp8s0: mtu 3000 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether 5a:00:04:ef:40:23 brd ff:ff:ff:ff:ff:ff ``` ## Next Steps - Use `ip neigh` to inspect and manage the ARP/neighbor table on your server. - Persist static routes and IP addresses in your distribution's network configuration so they survive a reboot. - Combine `ip -br` output with a monitoring script to alert on interfaces that drop to a `DOWN` state. - Run `man ip` for the full list of `ip` objects and commands beyond what's covered here. For the full guide with additional tips, visit the original article on [**Vultr Docs**](https://docs.vultr.com/how-to-use-the-linux-ip-command-to-manage-server-network-interfaces).