Learn to bring up an interface, assign an address and make the configuration persistent using real commands. 15.11.2025 | reading time: 3 min Manual configuration teaches how packets actually flow: this short guide shows how to bring an interface up, assign a static IP, add a default route and persist the setting so the change survives a reboot. Live example: set a static address now Do this on a test machine to see immediate results: run the commands and observe the interface state and address; example session: ```sudo ip link set dev eth0 down sudo ip addr flush dev eth0 sudo ip addr add 192.168.50.10/24 dev eth0 sudo ip link set dev eth0 up sudo ip route add default via 192.168.50.1 dev eth0 ip addr show eth0 # sample output 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000 inet 192.168.50.10/24 brd 192.168.50.255 scope global eth0 valid_lft forever preferred_lft forever``` Make it persistent and extend it A runtime change vanishes after reboot, so write the distribution-appropriate file: Debian-style example file content: ```auto eth0 iface eth0 inet static address 192.168.50.10 netmask 255.255.255.0 gateway 192.168.50.1 dns-nameservers 8.8.8.8 8.8.4.4``` or Red Hat-style: ```DEVICE=eth0 BOOTPROTO=none ONBOOT=yes IPADDR=192.168.50.10 NETMASK=255.255.255.0 GATEWAY=192.168.50.1 DNS1=8.8.8.8``` and remember you can also tweak MTU with `ip link set dev eth0 mtu 1400`, add a second address with `ip addr add 192.168.50.11/32 dev eth0`, or create a VLAN with `ip link add link eth0 name eth0.100 type vlan id 100`. When to use which tool Manual `ip` commands are perfect for quick tests and automation scripts; for persistent, distro-native control choose NetworkManager, systemd-networkd or netplan; use `dhclient` or your DHCP client when you need addresses from a server, and call service controls like `systemctl restart network` only after you have updated the correct config file for your distribution. Finish line and next steps You have seen how to change an interface now, persist a static configuration and extend the setup for routes, VLANs and MTU; practise on a lab VM, automate with scripts and then broaden theory toward certifications like CompTIA Linux+ or LPIC-1 with intensive exam preparation at bitsandbytes.academy to turn hands-on skill into credentials. Join Bits & Bytes Academy First class LINUX exam preparation. network troubleshooting infrastructure
