The Network Utility is a program that comes with modern Macs, as part of OSX, which has a number of different utilities to help give information on a network and perform simple tasks. In a basic install, the Network Utility resides in /Applications/Utilities, and has the name Network Utility.app. The Network Utility provides nine core aspects of functionality: Info, Netstat, AppleTalk, Ping, Lookup, Traceroute, Whois, Finger, and Port Scan.
The Info feature of the utility allows a user to easily find information on the network reached through different interfaces, which are accessible through a dropdown menu. Information includes the hardware address being used, the IP address assigned, the link speed, link status, and vendor information on the network adapter. It also provides traffic information, including incoming and outdoing packets. While it doesn’t have advanced troubleshooting features, it does show errors in both incoming and outgoing packets, and provides a collision count.
The Netstat feature allows for a greater degree of information on network activity than the simple Info. This includes information separated into TCP info, including detailed packet stats, UDP info with information about datagrams, as well as ICMP, IGMP, IPSec, IP6, ICPM6, IPSec, RIP6, and PFKey info. Netstat can also provide a routing table, with comprehensive information included. It can also show multicast data, and show the current state of all sockets the computer might have open, closed, or waiting.
For computers using AppleTalk, the Network Utility offers a number of diagnostics, including statistics and error counts, and all zones on a network. The Ping utility used by the program is similar to other ping services, allowing input of a destination address, and a set number of pings to be sent. For each ping, of 64 byte packets, a transit time is given, helping troubleshoot network connections.
The Lookup included in the utility allows for a comprehensive examination of hosts. Basic information can be displayed in one block, but more specific queries can be given as well. The Lookup utility can return information on the internet address, canonical name, CPU/OS type, mailboxes, mailbox exchange, name servers, host names, start of authority, text information, and well-known services. It also provides an option to display all of this information in one panel.
The Traceroute, Whois, and Finger options of the utility are all analogous to those found in other operating systems. Traceroute displays the full route from the host computer to the destination, with hop times listed. Whois queries a whois service to return information on a domain name registrant. The Finger utility allows a user to look at a specific user profile on a specific server.
The Port Scan feature of Network Utility allows for a range to be examined for open ports. This can be designated either by domain name or by IP address, and a scan can be set to search for all open ports, or to search only within a certain range. Port scanning is useful both for mapping networks, and for network security. By running a port scan, a network administrator can find potential weaknesses in the network and patch them before they are exploited by a malicious person.
