The traditional ping command (ICMP protocol) doesn't support port specification. Instead, we need alternative methods to test TCP/UDP port connectivity:

telnet example.com 80

If the port is open, you'll see either a blank screen or service banner. For HTTP port 80:

Connected to example.com.
Escape character is '^]'.

Modern tools provide better port testing capabilities:

1. Netcat (nc)

nc -zv 192.168.1.100 22

Example output for SSH port:

Connection to 192.168.1.100 22 port [tcp/ssh] succeeded!

2. Nmap for Advanced Scanning

nmap -p 443 google.com

Sample output:

Starting Nmap 7.92 ( https://nmap.org )
Nmap scan report for google.com (142.250.190.46)
PORT    STATE SERVICE
443/tcp open  https

For Windows systems without external tools:

Test-NetConnection -ComputerName server.example.com -Port 3389

Or using .NET class:

$tcp = New-Object System.Net.Sockets.TcpClient
try {
    $tcp.Connect("example.com", 3306)
    Write-Host "Port 3306 open"
} catch {
    Write-Host "Port 3306 closed"
}

A reusable Python solution:

import socket

def check_port(host, port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.settimeout(2)
    result = sock.connect_ex((host, port))
    sock.close()
    return "open" if result == 0 else "closed"

print(f"SSH port status: {check_port('example.com', 22)}")

• Firewall rules may block probes even if service is running
• UDP ports require different approaches (nc -u for netcat)
• Consider rate limits when scanning remote systems
• For production monitoring, look at Nagios/Zabbix solutions

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The traditional ping command only checks ICMP echo replies at the network layer (Layer 3), which doesn't provide port-level (Layer 4) connectivity information. This limitation often frustrates developers who need to verify if a particular service is listening on a specific port.

Here are the most practical methods to test port availability:

1. Using Telnet (Quick Check)

telnet example.com 80

If the port is open, you'll see either a blank screen (TCP connection established) or service-specific output. For closed ports, you'll get connection refused errors.

2. Netcat (nc) - The Swiss Army Knife

nc -zv example.com 443

This tests TCP connectivity (-z for zero I/O mode, -v for verbose). For UDP ports:

nc -zvu example.com 53

3. PowerShell Test-NetConnection

Test-NetConnection -ComputerName example.com -Port 3389

This provides detailed TCP connection test results including latency measurements.

For scripting purposes, these approaches work best:

Bash Function for Port Testing

port_check() {
  timeout 2 bash -c "</dev/tcp/$1/$2" && echo "Open" || echo "Closed"
}
port_check example.com 22

Python Solution

import socket
def check_port(host, port):
    try:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.settimeout(2)
            return s.connect_ex((host, port)) == 0
    except:
        return False

For comprehensive network troubleshooting:

• Nmap: nmap -p 80,443 example.com
• Hping3: hping3 -S -p 80 -c 3 example.com
• Curl: curl -v telnet://example.com:22

Remember that firewalls, NAT, and security groups can affect port accessibility. Always test from both internal and external networks when troubleshooting connectivity issues.