Top 10 free open source tools for network admins

From troubleshooting DNS queries and misbehaving network apps to keeping your configurations and passwords organized, these tools have you covered

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IPplan is not a generic spreadsheet or database application. It is tailored to tracking IP addresses, so it understands and enforces CIDR blocks. Each address record has support for contact info, hardware, DNS name, location, description, MAC address, NAT address tracking, and a generic "additional information" field. You can also upload a file to attach to the IP address record.

IP address records are organized into subnets (CIDR blocks), which are assigned to customers or autonomous systems. Subnets are further organized into network areas or ranges (supernets) within the customer hierarchy. Because IPplan is designed for use by ISPs, it works well for organizing enterprise addresses for companies with multiple locations and complex networks that use multiple AS (Autonomous System) numbers. If you decide to rework the subnets on your network, no problem. IPplan handles changes easily via its split and merge subnet functions, allowing you to split and merge subnets without losing any data.

You can import your existing IP allocation data via a CSV file upload. Alternatively, you can use an XML file created by Nmap to import addresses, or you can define the subnets yourself and have IPplan automatically fill in the DNS names for you. IPplan can import the DNS info via a zone transfer from your DNS servers.

You can set up multiple logins, so the entire network admin team has access to the IPplan database. You could even give the system administrators access to IPplan and require them to request IP addresses from you via the Web GUI.

IPplan is more than just an IP address tracking database. As you can see, you can also use IPplan to manage your DNS records, and IPplan implements "triggers" that allow you to run custom scripts based on actions taken in the Web interface.

Top free open source tools for network admins: IPplan

Top free open source tools for network admins: Tcpdump and Wireshark

When things get really hairy and you can't figure out what's going wrong on your network, it's time to pull out Tcpdump. This utility lets you capture the network traffic on a network card and view the packets and frames in real time.

If you're wondering why a browser can't find the Web server, you can fire up Tcpdump and see what's happening. Is the computer sending out DNS queries? Is it receiving a valid reply from the correct DNS server? By viewing the query and reply packets with Tcpdump, you can determine if the DNS server is replying with NXDomain for what should be a perfectly valid domain name or if the user changed the DNS server settings because he thinks that Google's DNS servers "must be faster" than your company's own servers. Or maybe the DNS queries and replies are fine, but the remote Web server is not responding. Then you would see the HTTP request packet leave the computer, but no replies from the Web server.

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