> For the complete documentation index, see [llms.txt](https://documentation.hak5.org/packet-squirrel-mark-ii/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.hak5.org/packet-squirrel-mark-ii/payload-development/duckyscript-for-packet-squirrel/killport.md).

# KILLPORT

The `KILLPORT` command inspects network traffic for activity on the specified ports.  Traffic on those ports will be killed with TCP FIN packet injection.

## Options

The `KILLPORT` command expects several options:

```
KILLPORT [interface] [port] ... [portN]
```

{% hint style="info" %}
The `KILLPORT` command only works on TCP connections; the FIN injection method required to terminate a connection is part of the TCP protocol.
{% endhint %}

### Interface

`KILLPORT` requires a network interface.  Typically on the Packet Squirrel this is `br-lan`, the virtual interface which connects the Ethernet ports.

### Ports

`KILLPORT` can match any number of ports.

## Examples

The `KILLPORT` command can be used as part of a payload to prevent traffic on the specified ports.

```bash
#!/bin/bash 

# Title: Killport example
#
# Description: Act as a transparent bridge but block HTTPS traffic

# Set bridge mode
NETMODE BRIDGE

LED G SINGLE

# Kill https on port 443
KILLPORT br-lan 443
```