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This article is about how to use Shell scripts to see if ports on multiple servers are open. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Introduction to nc command

Nc is the abbreviation of the English word netcat. It reads or writes data through the connection of the network protocol of TCP or UDP, and can be directly called by third-party programs or scripts.

At the same time, it is a very powerful network debugging tool because it can create almost all the connections you need.

There are three main functional modes of nc tools: connection mode, monitoring mode and channel mode. Its general usage format is as follows:

$nc [- options] [HostName or IP] [PortNumber]

Next, we use the Shell script combined with the nc command to implement our two requirements.

1. Scan whether a port on multiple servers is open

Here, we first put all the server addresses to be queried in a server-list.txt file, with each address on a separate line, as follows:

# cat server-list.txt 192.168.1.2 192.168.1.3 192.168.1.4 192.168.1.5 192.168.1.6 192.168.1.7

Then, we use the for loop to scan the port of the corresponding server in server-list.txt to see if it is open. Here, we scan port 22 to see if it is open.

# vi port_scan.sh #! / bin/sh for server in `more server- list.txt` do # echo $I nc-zvw3 $server 22 done

Finally, we can give the script executable permissions.

$chmod + x port_scan.sh

After that, we can use this script to automatically check whether port 22 of multiple servers is open.

# sh port_scan.sh Connection to 192.168.1.2 22 port [tcp/ssh] succeeded! Connection to 192.168.1.3 22 port [tcp/ssh] succeeded! Connection to 192.168.1.4 22 port [tcp/ssh] succeeded! Connection to 192.168.1.5 22 port [tcp/ssh] succeeded! Connection to 192.168.1.6 22 port [tcp/ssh] succeeded! Connection to 192.168.1.7 22 port [tcp/ssh] succeeded!

two。 Scan whether multiple ports on multiple servers are open

Here, we also put all the server addresses that need to be queried in a server-list.txt file, each on a separate line. I'm not going to repeat the demonstration here.

At the same time, we also put the server ports to be queried in another port-list.txt file, with a separate line for each port, as shown below:

# cat port-list.txt 22 80

Then, we use the for loop to scan whether the ports listed in the corresponding server port-list.txt in server-list.txt are open. Notice that two for loops are used here, the first layer is the server list, and the second layer is the port list.

# vi multiple_port_scan.sh #! / bin/sh for server in `more server- list.txt` do for port in `more port- list.txt` do # echo $server nc-zvw3 $server $port echo "" done done

Finally, we can give the script executable permissions.

$chmod + x multiple_port_scan.sh

After that, we can use this script to automatically check whether multiple ports on multiple servers are open.

# sh multiple_port_scan.sh Connection to 192.168.1.2 22 port [tcp/ssh] succeeded! Connection to 192.168.1.2 80 port [tcp/http] succeeded! Connection to 192.168.1.3 22 port [tcp/ssh] succeeded! Connection to 192.168.1.3 80 port [tcp/http] succeeded! Connection to 192.168.1.4 22 port [tcp/ssh] succeeded! Connection to 192.168.1.4 80 port [tcp/http] succeeded! Connection to 192.168.1.5 22 port [tcp/ssh] succeeded! Connection to 192.168.1.5 80 port [tcp/http] succeeded! Connection to 192.168.1.6 22 port [tcp/ssh] succeeded! Connection to 192.168.1.6 80 port [tcp/http] succeeded! Connection to 192.168.1.7 22 port [tcp/ssh] succeeded! Connection to 192.168.1.7 80 port [tcp/http] succeeded! Thank you for reading! This is the end of the article on "how to use Shell scripts to check whether the ports of multiple servers are open". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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