To check if the port is open for remote connectivity of Ubuntu, several methods can be used. Some of the methods to check if a port is open are:<\/p>\n
- \n
- \u201cnetstat\u201d Method<\/li>\n
- \u201css\u201d command Method<\/li>\n
- \u201clsof\u201d command Method<\/li>\n
- \u201cnetcat\u201d Method<\/li>\n
- \u201cnmap\u201d Method<\/li>\n
- \u201cPowerShell\u201d Method<\/li>\n<\/ul>\n
Enabling Port 443 (Prerequisite)<\/strong><\/h2>\n
Before diving into the process of checking the status of ports, let\u2019s have a look at how we can enable Port 443 to \u201cLISTEN\u201d. Port 443 is used by web servers in the background and is disabled by default. To enable the port, we have to enable it from the configuration files of any of the running services like Apache or Node. To enable Port 443, first, redirect to the Apache2 directory using the command:<\/p>\n
cd<\/span> \/<\/span>etc\/<\/span>apache2<\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-1.png\")
<\/p>\nList the Apache2 directory files and look for the \u201cports.conf\u201d file using the command:<\/p>\n
ls<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-2.png\")
<\/p>\nOpen the \u201cports.conf\u201d file using the command:<\/p>\n
sudo<\/span> nano<\/span> ports.conf<\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-3.png\")
<\/p>\nThis will open the text editor for the \u201cports.conf\u201d file and in our case, only Port 80 is Opened and actively Listening:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-4.png\")
<\/p>\nEdit the file and add the line below:<\/p>\n
Listen 443<\/span><\/div><\/div>\nSave the file by pressing \u201cctrl+O\u201d and exit using \u201cctrl+X\u201d:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-5.png\")
<\/p>\nNow your Apache2 will use Port 443 for active listening.<\/p>\n
The detailed procedure for checking the status of Port 80 and 443 using all the mentioned methods is explained below.<\/p>\n
Method 1: Checking Port 80 & 443 Status Using \u201cnetstat\u201d Command<\/strong><\/h2>\n
The netstat <\/strong>command is used for configuring the network connectivity. To use netstat, install the \u201cnet-tools<\/strong>\u201d package first using the command:<\/p>\n
apt update -y<\/span> &&<\/span> apt install<\/span> net-tools -y<\/span><\/div><\/div>\nIt will take some time to download and install the packages.<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-6.png\")
<\/p>\nOnce downloaded, use the command below to get all the port details:<\/p>\n
sudo<\/span> netstat<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-7.png\")
<\/p>\nTo get the Port 80 and only the one with LISTEN status, use the command:<\/p>\n
sudo<\/span> netstat<\/span> -tulpn<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :80<\/span><\/div><\/div>\nHere, the \u201c-tulpn<\/strong>\u201d flag displays all the listening ports. The \u201cgrep<\/strong>\u201d is used to filter and in this case, it will filter the word \u201cLISTEN\u201d as well as display only the items matching \u201c:80<\/strong>\u201d which is the port number.<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-8.png\")
<\/p>\nThe output shows that Port 80 is Listening meaning it is Open.<\/p>\n
Now to get Port 443 and only the one with LISTEN status, use the command:<\/p>\n
sudo<\/span> netstat<\/span> -tulpn<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :443<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-9.png\")
<\/p>\nMethod 2: Checking Port 80 & 443 Status Using \u201css\u201d Command<\/strong><\/h2>\n
The \u2018\u2019ss\u201d command is used to display the socket statistics. The \u201css\u201d command can \u201cList all Sockets\u201d, \u201cList Listening Sockets\u201d, \u201cDisplay TCP and UDP Sockets\u201d, and can also display \u201cEstablished Connections\u201d. It is used as an alternative to the \u201cnetstat\u201d command as it is simple to use and is faster than the \u201cnetstat\u201d command. To use the \u201css\u201d command, use the command below:<\/p>\n
ss -tulpn<\/span><\/div><\/div>\nThis will display all the Listening Ports:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-10.png\")
<\/p>\nTo display only Port 80, use the \u201css\u201d command as follows:<\/p>\n
ss -tulpn<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :80<\/span><\/div><\/div>\nThe \u201c-tulpn<\/strong>\u201d flag will display all the listening ports. The \u201cgrep<\/strong>\u201d will filter the word \u201cLISTEN\u201d as well as display only the connections matching \u201c:80<\/strong>\u201d which is the port number.<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-11.png\")
<\/p>\nThe output above shows Port 80 is Open and is Listening.<\/p>\n
Similarly, to find if the Port 443 is open, the command will be:<\/p>\n
ss -tulpn<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :443<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-12.png\")
<\/p>\nMethod 3: Checking Port 80 & 443 Status Using \u201clsof\u201d Command<\/strong><\/h2>\n
The \u201clsof\u201d command means \u201cList Open Files\u201d and lists information about files currently opened by a process. Although it is used to list opened and in-process files, it can also be used to display information about network connections such as showing the open sockets. Use \u201clsof\u201d by running the following command:<\/p>\n
sudo<\/span> lsof -i<\/span> -n<\/span> -P<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :80<\/span><\/div><\/div>\nHere the flag \u201c-P\u201d shows the port number, \u201c-i\u201d shows the open sockets, and \u201c-n\u201d is responsible for showing the IP Address instead of remote hostnames:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-13.png\")
<\/p>\nHere, the \u201c4u<\/strong>\u201d indicates file descriptors for IPv6, \u201c0t0<\/strong>\u201d shows the status of Port 80 which is currently in LISTEN State, and \u201c31398<\/strong>\u201d indicates the process id.<\/p>\n
To find out about Port 443, use the command:<\/p>\n
sudo<\/span> lsof -i<\/span> -P<\/span> -n<\/span> |<\/span> grep<\/span> LISTEN |<\/span> grep<\/span> :443<\/span><\/div><\/div>\n\n\n
\n <\/th>\n<\/tr>\n<\/thead>\n<\/table>\n ![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-14.png\")
<\/p>\nMethod 4: Checking Port 80 & 443 Status Using \u201cnetcat\u201d Method<\/strong><\/h2>\n
The \u201cnetcat\u201d is another method to check the status of a Port. It is used to analyze network hosts by connecting to a TCP port. To use netcat, use the command given below:<\/p>\n
nc -zv<\/span> <<<\/span>strong><\/span>hostname<\/span><\/<\/span>strong>><\/span> <<<\/span>strong><\/span>port<\/<\/span>strong><\/span> number><\/span><\/div><\/div>\n\n\n
\n <\/th>\n<\/tr>\n<\/thead>\n<\/table>\n Here, the \u201c-z\u201d scans for open ports, \u201cnc\u201d is the command for netcat, and \u201c-v\u201d indicates whether the port is open or closed. As we want to check the status of Port 80 on host \u201ctaha khan\u201d, the command used will be:<\/p>\n
nc -zv<\/span> tahakhan 80<\/span><\/div><\/div>\n\n\n
\n <\/th>\n<\/tr>\n<\/thead>\n<\/table>\n ![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-15.png\")
<\/p>\nSimilarly, for Port 443, we will use:<\/p>\n
nc -zv<\/span> tahakhan 443<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-16.png\")
<\/p>\nMethod 5: Checking Port 80 & 443 Status Using \u201cnmap\u201d Method<\/strong><\/h2>\n
The \u201cnmap<\/strong>\u201d method is used to check the Port Status on a Host Machine<\/strong>. The \u201cnmap\u201d command is used as follows:<\/p>\n
nmap<\/span> -p<\/span> <<<\/span>strong><\/span>port<\/<\/span>strong><\/span> number><\/span> <<<\/span>strong><\/span>host<\/<\/span>strong><\/span> IP><\/span><\/div><\/div>\nHere, the \u201c-p\u201d flag is used to specify the Port.<\/p>\n
Before using \u201cnmap\u201d ensure it is installed. If not, use the following command to install:<\/p>\n
sudo<\/span> apt install<\/span> nmap<\/span> -y<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-17.png\")
<\/p>\nTo use the \u201cnmap\u201d command you need to know the IP Address of the Host Machine. Consider an example in my case where the Host System name is \u201ctahakhan<\/strong>\u201d and the Client is \u201cubuntu1\u201d. The Host Machine has IP Address \u201c192.168.184.130<\/strong>\u201d. To check the status of Port 80, use the command:<\/p>\n
nmap<\/span> -p<\/span> 80<\/span> 192.168.184.130<\/div><\/div>\nThe status of Port 80 of our Host Machine will be displayed:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-18.png\")
<\/p>\nPort 80 shows the State as Open meaning it is Listening. Similarly, to find the status of Port 443 of our Host Machine, execute the \u201cnmap\u201d command as shown below:<\/p>\n
nmap<\/span> -p<\/span> 443<\/span> 192.168.184.130<\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-19.png\")
<\/p>\nPort 443 is open as shown in the State status.<\/p>\n
Method 6: Checking Port 80 & 443 Status Using \u201cPowerShell\u201d <\/strong><\/h2>\n
With PowerShell in Ubuntu, you can use the TcpClient class to check the open ports. Before checking the connections and open ports, install PowerShell in Ubuntu using the command:<\/p>\n
sudo<\/span> snap install<\/span> powershell --classic<\/span><\/div><\/div>\n![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-20.png\")
<\/p>\nLaunch it using the command:<\/p>\n
pwsh<\/div><\/div>\nThe command line will change indicating PowerShell is initialized:<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-21.png\")
<\/p>\nCreate a file now where a script will be added. In our case, we create a file using the \u201cnano\u201d editor:<\/p>\n
nano<\/span> Port.ps1<\/div><\/div>\nThe \u201c.ps1\u201d extension indicates it is a PowerShell Script.<\/p>\n
![](\"http:\/\/linuxways.net\/wp-content\/uploads\/2023\/09\/word-image-21017-22.png\")
<\/p>\nThe text editor will open, and add the below script inside the \u201cPort.ps1\u201d file:<\/p>\n
[<\/span>CmdletBinding(<\/span>)<\/span>]<\/span>
\n[<\/span>OutputType(<\/span>[<\/span>System.Management.Automation.PSCustomObject]<\/span>)<\/span>]<\/span>
\nparam (<\/span>
\n[<\/span>Parameter(<\/span>Mandatory)<\/span>]<\/span>
\n[<\/span>string[<\/span>]<\/span>]<\/span>$SystemName<\/span>,
\n[<\/span>Parameter(<\/span>Mandatory)<\/span>]<\/span>
\n[<\/span>int[<\/span>]<\/span>]<\/span>$Port<\/span>,
\n[<\/span>Parameter(<\/span>)<\/span>]<\/span>
\n[<\/span>int]<\/span>$TcpTimeout<\/span> = 1000<\/span>
\n)<\/span>
\nbegin {<\/span>
\n$Protocol<\/span> = 'TCP'<\/span>
\n}<\/span>
\nprocess {<\/span>
\nforeach (<\/span>$System<\/span> in<\/span> $SystemName<\/span>)<\/span> {<\/span>
\nforeach (<\/span>$Portx<\/span> in<\/span> $Port<\/span>)<\/span>