1. Detailed explanation of the basic use of ping

Ping is a very powerful TCP/IP tool in the network. Its main functions are:

(1) Used to detect network connectivity and analyze network speed;

(2) Obtain the server IP according to the domain name;

(3) Determine the operating system used by the other party and the number of data packets passing through the router according to the TTL value returned by the ping.

We usually use it to directly ping the IP address to test the connectivity of the network.

Like this, directly ping the IP address or gateway, the ping will show the above data, some friends may ask bytes=32; time<1ms; TTL=128 what does this mean.

bytes value: the size of the data packet, that is, bytes.

 

 

Time value: response time. The smaller the time, the faster you connect to this address.

TTL value: Time To Live, which means the time that the DNS record exists on the DNS server. It is a value of the IP protocol packet and tells the router when the data packet needs to be discarded. The TTL value returned by Ping can be used to roughly determine whether the target system type is Windows series or UNIX/Linux series.

By default, the TTL value of the Linux system is 64 or 255, the TTL value of the Windows NT/2000/XP system is 128, the TTL value of the Windows 98 system is 32, and the TTL value of the UNIX host is 255.

 

Therefore, the general TTL value:

 

Between 100~130ms, Windows system;

 

Between 240~255ms, UNIX/Linux system.

 

Of course, our main understanding today is not these, but other references for ping.

 

In addition to directly ping the ip address of the network and verifying the smoothness and speed of the network, the ping command also has these usages.

 

2. Use of ping-t

 

Ping the designated computer without interruption until the administrator interrupts.

 

This shows that the computer is connected to the router and the network effect is good. Next, press Ctrl+c on the keyboard to terminate it and continue pinging, it will stop, and it will summarize how many data packets are running and how many are on and off.

 

3. Use of ping-a

 

Ping-a resolves the computer name and NetBios name. That is, the host name can be resolved by pinging its IP address.

 

4. Use of ping-n

 

By default, only 4 packets are generally sent. This command can be used to define the number of packets sent, which is very helpful for measuring network speed. For example, I want to test the average return time of sending 10 packets. , What is the fastest time and the slowest time can be obtained by the following:

 

From the above, it can be known that in the process of sending 10 data packets to 47.93.187.142, 10 were returned without loss. Among the 10 data packets, the fastest return speed was 32ms, the slowest 55ms, and the average speed was 37ms. It shows that my network is good.

 

If for some bad networks, such as the monitoring system is very lagging, the results returned by this test may show a part of the loss. If the amount of loss is relatively large, then it means that the network is not good, and it can be judged intuitively Network conditions.

 

5. Use of ping-I size

 

-l size: Send data packets of the size specified by size to the target host.

 

By default, the packet size sent by Windows ping is 32 byt, and the maximum can be 65500 byt. When a data packet sent at one time is greater than or equal to 65500 byt, it may cause the receiver's computer to crash. So Microsoft limits this value; this parameter is very harmful in the future when combined with other parameters. For example, an attacker can use the -t parameter to implement a DOS attack. (So ​​it is dangerous, don't use it easily on other people's computers).

 

For example, ping -l 65500 -t 211.84.7.46

 

Will continue to ping the IP address until it is interrupted by the user with Ctrl+C.

 

In this way, it will continuously send data packets with a size of 65500 byt to the 211.84.7.46 computer. If you only have one computer, it may not be effective, but if there are many computers, the other party can be completely paralyzed and the network will be seriously blocked. It can be seen that the power is not trivial.

 

 

6. Use of ping-r count

Record the routing of outgoing and return packets in the "Record Route" field, and detect the passing

The number of routes, but up to 9 routes can be traced. ping -n 1 -r 9 202.102.224.25 (send a data packet, record 9 routes at most)

 

All 9 routes will be displayed, you can see the picture above.

Ping commands are mostly used in these 6 types. You may use these in your projects. Here is a less commonly used but easy-to-use ping method.

7. Batch ping network segment

For a network segment with many IP addresses, if a single detection is really troublesome, then we can directly ping the network segment detection in batches, and it will be clear at a glance which IP address has a problem.

Look at the code first, and enter directly in the command line window: for /L %D in (1,1,255) do ping 10.168.1.%D

Modify the IP address segment to the IP address segment you want to check.

 

When the batch command is entered, it will automatically ping all the IP addresses in the network segment until it finishes.