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

# tunnelOverheadBytes

The number of bytes added to each tunneled packet for storing tunneling protocol headers.

## Declaration

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

## Discussion

Discussion The value of this property is subtracted from the Maximum Transmission Unit (MTU) of the tunnel’s underlying physical network interface to compute the MTU of the TUN interface.

## See Also

### Accessing network properties

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