nc - Netcat
Linux 系統中一個多用途的網路工具程式，雖然它只是一個小程式，但是能夠做的事情很多，就像瑞士刀一樣，幾乎任何使用 TCP 或 UDP 封包的動作都可以用它來達成，是許多系統管理者（包含我自己）最喜愛的網路診斷工具之一。
基本指令
# Scanning the port range (20 - 1024)
nc -z 192.168.21.202 20-1024
Connection to 192.168.21.202 22 port [tcp/ssh] succeeded!
Connection to 192.168.21.202 80 port [tcp/http] succeeded!
Connection to 192.168.21.202 111 port [tcp/sunrpc] succeeded!
Connection to 192.168.21.202 443 port [tcp/https] succeeded!
Connection to 192.168.21.202 514 port [tcp/shell] succeeded!
# Scanning the specified port
nc -zv 192.168.21.202 21
nc: connect to 192.168.21.202 port 21 (tcp) failed: Connection refused
# Port Scanning With netcat including displaying version #
echo "QUIT" | nc 192.168.2.17 22
echo "QUIT" | nc -v 192.168.2.254 ssh
# OR pass the -vv to get remote OpenSSH version #
nc -vv 192.168.2.254 ssh檔案傳輸
在不同的 Linux 主機上傳輸檔案
# Install nc and pv
yum install netcat pv
# Machine A with IP : 192.168.0.4
# Machine B with IP : 192.168.0.7
# On Linux Machine A
# [*] tar -zcf = tar is a tape archive utility used to compress/uncompress archive files
# and arguments -c creates a new .tar archive file, -f specify type of the archive file
# and -z filter archive through gzip.
# [*] CentOS-7-x86_64-DVD-1503.iso = Specify the file name to send over network, it can be file
# or path to a directory.
# [*] pv = Pipe Viewer to monitor progress of data.
# [*] nc -l -p 5555 -q 5 = Networking tool used for send and receive data over tcp
# and arguments -l used to listen for an incoming connection, -p 555 specifies the source port
# to use and -q 5 waits the number of seconds and then quit.
tar -zcf - CentOS-7-x86_64-DVD-1503.iso | pv | nc -l -p 5555 -q 5
# On Linux Machine B
nc 192.168.1.4 5555 | pv | tar -zxf -測試 TCP Port
nc -v 192.168.0.175 5000UDP 封包傳輸
# 本地主機，傳送字串至遠端主機
echo -n "foo" | nc -u -w1 192.168.1.8 5000
# 遠端主機，開啟 UDP port
nc -lu localhost 5000
Reverse Shell
