--- lastproofread: '2026-01-23' --- (loopback-interface)= # Loopback The loopback interface is a virtual, software-based network interface. All traffic sent to it loops back and only targets services on the local host. :::{note} Only one loopback `lo` interface is allowed per operating system. If you require multiple virtual interfaces, use the {ref}`dummy-interface` interface type. ::: ## Configuration ### Common interface configuration ```{cmdincludemd} /_include/interface-address.txt :var0: loopback :var1: lo ``` ```{cmdincludemd} /_include/interface-description.txt :var0: loopback :var1: lo ``` ## Operation ```{opcmd} show interfaces loopback Show brief interface information. :::{code-block} none vyos@vyos:~$ show interfaces loopback Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down Interface IP Address S/L Description --------- ---------- --- ----------- lo 127.0.0.1/8 u/u ::1/128 ::: ``` ```{opcmd} show interfaces loopback lo Show detailed interface information. :::{code-block} none vyos@vyos:~$ show interfaces loopback lo 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 RX: bytes packets errors dropped overrun mcast 300 6 0 0 0 0 TX: bytes packets errors dropped carrier collisions 300 6 0 0 0 0 ::: ```