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Network Management

Networking management in linux is a crucial to make a robust linux system. well at least we know some essential networking tasks, like configuring interfaces, managing IP addresses, setting up routing, and using firewalls.

Checking Network Interfaces​

To check the available network interfaces, use:

ip link show

Or using the deprecated ifconfig (requires installation on some distributions)

ifconfig -a

To display detailed interface information:

ip addr show

Configuring Network Interfaces​

To bring up or down a network interface:

sudo ip link set eth0 up   # Enable interface
sudo ip link set eth0 down # Disable interface

For ifconfig users (it's deprecated bro, leave it):

sudo ifconfig eth0 up
sudo ifconfig eth0 down

Managing IP Addresses​

To assign an static IP address to an interface temporarily:

sudo ip addr add 192.168.1.10/24 dev eth0

To make changes persistent, edit the /etc/network/interfaces configurations (Debian based).

/etc/network/interfaces
auto eth0
iface eth0 inet static
    address 192.168.1.100
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 8.8.8.8 8.8.4.4

or edit /etc/sysconfig/network-scripts/ifcfg-eth0 if u use RHEL-based systems.

To remove an IP address:

sudo ip addr del 192.168.1.10/24 dev eth0

To check current IP addresses:

ip a

Routing and Default Gateway​

To check routing information:

ip route show

To add a default gateway:

sudo ip route add default via 192.168.1.1

To remove a default gateway:

sudo ip route del default

Managing Network Services​

To check the status of the networking service:

sudo systemctl status networking

To restart networking:

sudo systemctl restart networking

To enable network services at boot:

sudo systemctl enable networking

For NetworkManager users:

nmcli connection show
nmcli device status

Troubleshooting Network Issues​

To check connectivity:

ping 8.8.8.8

To check DNS resolution:

nslookup google.com

To trace network routes:

traceroute google.com

To analyze network traffic:

tcpdump -i eth0

To check open ports:

sudo netstat -tulnp

Or using ss (modern alternative):

ss -tulnp