Recommended Freeware applications for network troubleshooting

Engage Packet Builder — 98/ME/NT/2000/XP
Engage Packet Builder is a powerfull and scriptable libnet-based packet builder for Windows. Features include packet injection starting from the link layer, custom payload in hex or ASCII format, scripting engine, and more.

Auditor Security – OS independent
The Auditor security collection is a bootable CD based on KNOPPIX that does not require installation. The analysis platform is started directly from the CD-Rom and is fully accessible within minutes. Independent of the hardware in use, the Auditor security collection offers a standardised working environment with a toolset consisting of about 300 professional open-source programs for foot-printing, analysis, scanning, wireless, brute-forcing, cracking.

Network Notepad — 98/ME/NT/2000/XP
Network Notepad is a program for creating interactive network diagrams with user-definable management features such as point-and-click telnet.

SuperScan — 98/NT/ME/2000
SuperScan is a powerful TCP port scanner, pinger, and resolver. Features include superior scanning speed, support for unlimited IP ranges, improved host detection using multiple ICMP methods, TCP SYN scanning, UDP scanning (two methods), IP address import supporting ranges and CIDR formats, simple HTML report generation, source port scanning, fast hostname resolving, extensive banner grabbing, massive built-in port list description database, IP and port scan order randomization, a selection of useful tools (ping, traceroute, Whois etc), extensive Windows host enumeration capability.

  ItCan.Net Monitor — 98/ME/NT/2000/XP
ItCan.Net Monitor is a bandwidth analysis utility. Besides giving a graphical illustration of the bandwidth usage on your computer or the network it resides, you get a list of all incoming and outgoing connections. This way you know exactly how your bandwidth is used. You can also use it to monitor the connections, see how many people are downloading heavily from the Internet, see how many people are using those chat programs. ItCan.Net Monitor will tell you everything you need to know. Like a network sniffer it will analyse the packets and display them to you the way you want it to, textual, graphical or a combination of the two.

WinPcap Network Packet Capture Driver — 98/ME/NT/2000/XP
WinPcap is an architecture for packet capture and network analysis for the Win32 platforms. It includes a kernel-level packet filter, a low-level dynamic link library (packet.dll), and a high-level and system-independent library (wpcap.dll, based on libpcap version 0.6.2). The packet filter is a device driver that adds to Windows 95, 98, ME, NT, 2000, XP and 2003 the ability to capture and send raw data from a network card, with the possibility to filter and store in a buffer the captured packets.

GFI LANguard Network Security Scanner — 98/ME/NT/2000/XP
GFI LANguard Network Security Scanner (N.S.S.) checks your network for all potential methods that a hacker might use to attack your network. By analyzing the operating system and the applications running on your network, GFI LANguard N.S.S. identifies possible security holes. In other words, it plays the devil’s advocate and alerts you to weaknesses before a hacker can find them, enabling you to deal with these issues before a hacker can exploit them. GFI LANguard N.S.S. scans your entire network, IP by IP, and provides information such as service pack level of the machine, missing security patches, open shares, open ports, services/applications active on the computer, key registry entries, weak passwords, users and groups, and more. Scan results are outputted to an HTML report, which can be customized/queried, enabling you to proactively secure your network – for example, by shutting down unnecessary ports, closing shares, installing service packs and hotfixes, etc.

Demarc PureSecure Personal Edition — 98/ME/NT/2000/XP
Demarc PureSecure is a one of a kind, Total Intrusion Detection System (TIDS), which provides an unsurpassed level of comprehensive security. For the first time you will be able to reliably prevent, detect, and deter internal and external threats to your organization’s valuable assets with complete confidence, 24 hours a day. Advanced cross platform compatible technology means PureSecure can be deployed and scale in a wide variety of network infrastructures.

Sam Spade — 98/ME/NT/2000/XP
Sam Spade is a network query tool. Included tools are ping, nslookup, whois, IP block whois, dig, traceroute, finger, SMTP VRFY, web browser, keep-alive, DNS zone transfer, SMTP relay check, Usenet cancel check, website download, website search, email header analysis, Email blacklist query, Abuse address query, S-Lang scripting, Time.

Ethereal Network Analyzer — 98/ME/NT/2000/XP
Ethereal is a network protocol analyzer for Unix and Windows which can capture data directly from various types of live network connections or read capture files in many different formats. Output can be saved or printed as plain text or PostScript, data display can be refined using a display filter, display filters can also be used to selectively highlight and color packet summary information, all or part of each captured network trace can be saved to disk.

Active Ports — NT/2000/XP
Active Ports – easy to use tool that enables you to monitor all open TCP/IP and UDP ports on the local computer. Active Ports maps ports to the owning application so you can watch which process has opened which port. It also displays a local and remote IP address for each connection and allows you to close any port. Active Ports can help you to detect trojans and other malicious programs.

NetStat Live — 98/ME/NT/2000/XP
AnalogX NetStat Live is a small, easy to use TCP/IP protocol monitor which can be used to see your exact throughput on both incoming and outgoing data – whether you’re using a modem, cable modem, DSL, or local network. It lets you see how quickly your data goes from your computer to another computer on the Internet, it will tell you how many other computers your data must go through to get there. NSL also graphs your CPU usage of your system.

IP Subnet Calculator — 98/ME/NT/2000/XP
The IP Subnet Calculator is a utility for computing information about class A, B, or C IP addresses such as address info, subnet and host tables, and supernetting / CIDR.

UltraVNC — 98/ME/NT/2000/XP
Ultr@VNC is a client/server software that allows you to remotely control a computer over any TCP/IP connection as if you were in front of it. Features include toolbar and hotkeys, high speed, MS logon/NT security/Active Directory support, embedded file transfer and chat, and more.

eEye Digital Security Tools — 98/ME/NT/2000/XP
This is a collection of free network security tools, specifically programs that scan class C networks for specific vulnerabilities such as Nimda, CodeRed, SQL Worm, Apache Chunk, etc. and alert you of any machines that are vulnerable or infected.