Network Tools

Network Tools

This application contains simple network tools:

Features

• ping
• nslookup
• netstat
• traceroute
• Port scanner

What this tool does not do

• Advanced network tests

General usage

For ping, traceroute, nslookup and netstat: Just select the tab of the tool you use, enter a value or command in the text box and press Enter or click the button. The result of the command will render in the Command Output view.

If checked the box "Auto-clear console" will clear the output view before running the command the next time you execute it.

You can set the paths to the correct OS commands to use in the preferences (see the end of this page).

The port scanner

The port scanner allows you to test if some TCP and UDP ports are open on a host.

So, the first thing to do is select the protocol (TCP or UDP) and enter the name or IP of the host to test. Finally set a range of ports to scan. The ports are tested every second (this delay cannot be configured yet).

There are some advanced settings to allow you scan in different manners:

• Delay (possibly random) between 2 scanned ports
• Random scanning: before being scanned, the ports designated in the range are randomly ordered then scanned.
• Batch scanning: this allows you to group the ports to be scanned and pause between the groups. The Batch Size is the number of ports you put in a group and Sleep Duration is a amount of seconds the scanner waits between two groups. As said, ports are scanned every second in a group.

The output of the command is as follows. It is quite a standard format for port scanners:

[port number]/[port state]/[protocol (tcp or udp)]/[optional known protocol that uses this port]

Example:

1/close/tcp/tcpmux
2/close/tcp/
3/close/tcp/
4/close/tcp/
5/close/tcp/rje

The port states are the following:

• close: the port is closed
• open: the port is open
• filtered: UDP only. The scanner could not determine if the port is closed or open.
• open|filtered: UDP only. The port is open or filtered.
• unknown: UDP only. Any other state (should never exist).

Assessing the state of a UDP port is tricky because there is no guarantee that a reply datagram will be sent back to the client. The algorithm behind the scanner is inspired from nmap.

The known protocols are basically those coming from the standard Unix /etc/services file. See [Network Tools/attachment/ports.properties] for the complete list.

About the implementation

These tools, except the port scanner, are simply the OS commands. I did this for simplicity reasons and also because Java does not offer advanced support for working with networks. For example you cannot forge ICMP packets (or at least I have not found how to do that :)).