1. Ping
Purpose: ping is a utility used to test whether a network device or network issue, called a host, is reachable by sending one or more ICMP Echo Request packets, then waiting for the echo reply.
Steps:
Open the CLI:
· Windows: Open Command Prompt.
· Linux/macOS: Open Terminal.
· Basic Ping Command:
At the command line, type ping <hostname or IP address>. For example, ping google.com or ping 192.168.1.1
· Press Enter.
· Analyze the results:
Successful Ping: You will receive replies showing the round-trip time.
Request timed out" or "Destination host unreachable" messages indicate a problem.
Advanced usage options:
· Continuous ping, namely: ping -t <IP address> in Windows, or ping <IP address> in Linux/macOS, with Ctrl+C to stop it.
· Limit the number of pings: ping -n 10 <IP address> in Windows, or ping -c 10 <IP address> in Linux/macOS.
Increase the packet size to test with bigger packets: ping -l 1000 <IP address> in Windows.
Uses:
· Testing a network connection Checking for latency, that is network delay.
· Such might be the indication of packet loss or very high latency spikes, which could be a symptom of network congestion or any other problem.
2. Traceroute
Description: traceroute (or tracert on Windows) shows the route that packets take from the source machine to destination. Moreover, it allows measuring delay at each hop.
Prerequisites
Open the CLI:
· On Windows: Open Command Prompt.
· On Linux/macOS: Open Terminal.
Run Traceroute:
· On Windows: tracert <hostname or IP address>.
· On Linux/macOS: traceroute <hostname or IP address>.
Press Enter.
Analyze the output:
· Each line represents a hop from source to destination.
· The first column is a hop number
· Next columns are the round-trip times for each probe
· The last column is the IP address or hostname of the device at each hop.
· Note where latency increases or timeouts happen, thus showing network bottlenecks or failures.
Use Cases:
· Diagnosing routing issues
· Identifying slow or failing network segments
· Locate where packets are dropped in a network.
3. IP Scanners
Purpose: An IP scanner is used to scan a range of IP addresses in a network to identify active devices and open ports.
Popular Tools:
· Angry IP Scanner: It is a cross-platform IP scanner with a GUI.
· Nmap: A very powerful network scanning tool used for network discovery and security auditing.
Steps (Using Nmap):
Installation of Nmap:
· On Linux: sudo apt-get install nmap
· On macOS: brew install nmap
· On Windows: download and install from the official Nmap website.
Basic IP Scan:
Open CLI.
· Type nmap –sn, followed by the IP range. For example, type nmap –sn 192.168.1.0/24.
· Press Enter.
· The Output:
· All active IP addresses with corresponding MAC addresses will be listed.
Advanced Scanning:
· Port Scanning: The command nmap -p 1-65535 is used to scan all ports on any particular IP address.
· Service/Version Detection: The command nmap –sV is used to identify the services running on open ports on any particular IP address.
Use Cases:
· The detection of unauthorized devices on a network
· The identification of open ports, which might give security risks
· The mapping of devices on a network
4. Subnet Calculators
Purpose: Subnet calculators are used to evaluate the correct subnet mask, network address, and broadcast address for a given IP address range.
Popular Tools:
· Online Subnet Calculators: Fast, easy access, quick results.
· SolarWinds Advanced Subnet Calculator: Downloads, but offers more features for admins.
Steps:
Inputting Address and Mask:
· Provide an IP address (e.g., 192.168.1.0) and subnet mask (e.g., 255.255.255.0) in the calculator.
Calculate Subnet Details:
Calculator Output:
· Network Address: The first address of the subnet.
· Broadcast Address: The last address of the subnet.
· Number of Hosts: This is the total number of usable IP addresses in the subnet.
Use for Planning:
· Use this information in the configuration of devices on a network.
· Plan and implement the use of IP addresses within the subnet to ensure no conflicting addresses are used.
Use Cases:
· When planning IP address allocation in a network.
· Configuration of network devices with the correct subnet mask and IP ranges.
· Troubleshooting issues of IP address conflicts.
5. Putting the Utilities Together for Troubleshooting
· In troubleshooting or analyzing network problems, these utilities can be deployed together in the following ways:
· Use Ping to first verify a connection.
· Utilize Traceroute to isolate where the problem is situated on the network path.
· Run an IP Scanner to determine all devices connected to the network. It allows for the discovery of unauthorized or unusual devices connected.
· Use a Subnet Calculator to test the network configuration. In particular, it is used when subnetting problems are suspected.
· Taken together, these utilities make for a full-function toolkit for network diagnostics and troubleshooting. They let IT professionals work through network problems in a quite orderly way.
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