PPTP Ping Diagnostics for Win2000

I. Introduction to Functions

PPTP is the abbreviation of "Point-to-Point Tunneling Protocol". Point-to-point tunneling is a commonly used transport protocol on the network. The so-called "tunneling" means that the data is encrypted and "packaged" before being transmitted, and then transmitted to the other party before being unpacked and decrypted. In this way, the data is transmitted in the underground tunnel as it is passed, and its contents are not seen by the outside world, so "tunnel transmission". For more detailed understanding, please refer to the relevant information. If the transfer fails, a specific diagnostic must be used to find the cause. We used the Ping command when testing network connectivity. This has been mentioned in the previous article. For PPTP diagnostics, similar commands are required. In the windows2000 Support Tools folder, you can find Pptpclnt.exe and Pptpsrv.exe, two programs, this is the tool we want, Pptpclnt.exe for the client, Pptpsrv.exe for the server. It is a group of tools that must be used in conjunction with each other.

When using the above two programs for mutual access between a remote PPTP server and a PPTP client, port 1723 must be used and support based on Type 47 protocol is required. The Type 47 protocol refers to the GRE (Generic Routing Encapsulation) protocol, so ensure that the above conditions are met before running Pptpclnt.exe and Pptpsrv.exe. In addition, pay special attention to: PPTP Ping can run on windows2000, windowsNT and windows98, but can not run on windows95!

II. Usage

This set of programs are based on the command line interface. Since the diagnosis must involve both the PPTP server and the PPTP client, when the diagnostic program is running, it is necessary to synthesize the response information and system prompt information of the server and client, and then judge the problem according to the situation. PPTP Ping can be used to test many projects of the PPTP server. Below we introduce the project classification and introduce the prompt information of both the server and the client. And the following statement is agreed: the PPTP server is at site A, and the PPTP client is at site B.

1. Test the connectivity of PPTP.

(1) Run Pptpsrv.exe on the computer at Site A.
(2) Run Pptclnt.exe on Site B, the command should indicate the server name or IP address. For example: Pptclnt.exe[[servername or IPaddress]

At this point, you can see the following tips on the server side: (The original text is English, the following is translated into Chinese)

pptpsrv

Must be sure to run pptpclnt.exe on the client side
Wait (using TCP port 1723) to connect. . . . . .
The connection to the client has been successful!
Data sent from the client:
---> abcdefghijklmnopqrstuvwxyz
Send 'Reply from server' message to the client side.
Establish a socket test based on the GRE protocol. . .
is accepting GRE packets based on Type 47 protocol. . . .
Total GRE packets received = 1
Total GRE packets received = 2
Total GRE packets received = 3
Total GRE packets received = 4
Total GRE packets received = 5

(3) Finally, the test is completed. If you need to test the PPTP connection between this server and another client, repeat the above steps.
(4) For the sake of comparison, here is also the screen prompt information on the client side when the above test is performed. (The original text is English, the following is translated into Chinese)

pptpclnt jade (jade is the server name)

Initial socket...
Find host information...< BR> has successfully received the server host information
type the information sent to the server (used to test connectivity). The characters used for sending should be less than 255. For example:
-->abcdefghijklmnopqrstuvwxyz

Successfully connect to PPTP over TCP port 1723. Now the data is being sent to the server jade. On dns.microsoft.com. . .

Wait for sending end...
Received the end of the response, the response message should be the following text:
---> Hello, there! This is a reply from the server.
Use port 1723, TCP protocol connectivity test succeeded
Close socket...

Create socket for testing GRE protocol...
(The following tips are sent to the other end )
Total GRE packets sent = 1
Total GRE packets sent = 2
Total GRE packets sent = 3
Total GRE packets sent = 4
Total GRE packets sent = 5

If the GRE package is sent to the other party, check if the other server is successfully accepted.
Close the socket