---
title: mtu
framework: networkextension
role: symbol
role_heading: Instance Property
path: networkextension/nepackettunnelnetworksettings/mtu
---

# mtu

The size of the maximum trasnmission unit, in bytes.

## Declaration

```swift
@NSCopying var mtu: NSNumber? { get set }
```

## Discussion

Discussion The maximum transmission unit (MTU) size represents the largest number of bytes that anything can assign to the TUN interface. note: The system ignores the tunnelOverheadBytes property when this property is non-nil.

## See Also

### Accessing network properties

- [ipv4Settings](networkextension/nepackettunnelnetworksettings/ipv4settings.md)
- [NEIPv4Settings](networkextension/neipv4settings.md)
- [ipv6Settings](networkextension/nepackettunnelnetworksettings/ipv6settings.md)
- [NEIPv6Settings](networkextension/neipv6settings.md)
- [tunnelOverheadBytes](networkextension/nepackettunnelnetworksettings/tunneloverheadbytes.md)