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---
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: <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
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
:::
```
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