Network management via Telnet
Managing equipment over the Internet has become quite the buzz with the advent of embedded Web servers in WAN and LAN equipment. There are many user options depending on the products being managed. There are, however, a few wrinkles-thanks to hackers, spammers and general security concerns IT managers have resorted to a twisted Web of firewalls, gateways, proxy servers and subnets to protect their equipment and users from the dangers of the open Internet. This is where the wrinkles come in. Access to equipment may be limited or tricky when you are on the wrong side of that wall of protection. Without addressing all of this, it is safe to say that managing T1 and DSL access equipment from the unwashed Internet may require a sitdown with your IT manager. So what can be done?
As long as the device you want to manage has an Ethernet port, you have access to the world of IP and the wonders of protocols like SNMP, Telnet, HTTP, TFTP and SMTP. Of those, SNMP tends to chain network managers to specific fixed IP workstations and also implies expensive management systems. But with the other protocols, the user is mobile because management access is available from any Internet connection with the use of low-cost or even free applications.
Telnet was created early in the life of the Internet and remains one of its most useful applications. It provides an Internet virtual terminal interface so that, from a user's perspective, it is like being directly connected to a device's terminal port. The user management capability is dependent on the native terminal user interfaces. Older equipment will have command line or menu tree user interfaces; modern equipment should use object orientation and Web browser paradigms of frames and links.
A major Telnet advantage is complete access to all the parameters and diagnostic controls of the managed unit. Many status displays are dynamically updated, unlike with SNMP. If you have a Windows PC, you already have Telnet. To run Windows Telnet, press the Windows Start button and select Run. Type in "Telnet xxx.xxx.xxx.xxx," where the xxxs are the IP of the managed device. In due time, Telnet will present you with a terminal window. The default terminal emulation will be VT100, but you will have to make a change to the Terminal Preferences for the arrow keys to work. Type "alt-T" for the Terminal menu, then "P" for Preferences, check the VT100 Arrows box and finally the OK button. You will now be able to navigate within the Telnet window using the PC's arrow cursor keys-your mouse won't work inside the terminal image. Windows Telnet remembers the IP addresses you have entered and presents them in a choice list so you won't have to enter them every time. Telnet's fast response times and the ability to use the ultimate in mobile PC alternatives, Window CE H/PCs, make it a favorite. For handhelds, you will need a separate Telnet package; another possibility is Telnet Force from www.Ruksun.com.
Embedding Web servers in WAN access equipment is a recent occurrence, but more are soon to follow. These Web servers provide the GUI of the future. One might call them a graphical Telnet. Best of all, almost any Web browser will work. The power of graphics can make equipment very easy to control, but unlike a Telnet session, where every step of the user's interaction is cognizant of all previous steps, each step with a Web browser is a separate session. A browser is good for viewing status snapshots and executing controls like loop-backs. Making configuration changes can be problematic if multiple users are accessing the Web server for changes. Nonetheless, the advantages of Web browsers are compelling.
To access an IP address with a browser, click on the address bar to select it and type in "HTTP://xxx.xxx.xxx.xxx." Depending on the managed equipment, you may need to add a specific HTML page such as "HTTP://xxx.xxx.xxx.xxx/login.html." Refer to the documentation of the equipment you are accessing. Once you have entered the address, the home page of the device will be displayed. Again, you can use a Windows CE H/PC, but this time the software is built in, Pocket Internet Explorer. The rather basic Web browsers of Windows CE and other handheld computers may not support all the HTML commands used by the managed device's embedded Web server. When your browser does not support enough HTML, Telnet is still a good solution.
When it comes to updating WAN access equipment with new features or-perish the thought-bug fixes, TFTP (Trivial File Transfer Protocol) provides a reliable solution. TFTP software does not come with Windows PCs, but it is readily available from a number of software vendors even as shareware. Other Internet protocols could be used, but TFTP is popular in embedded devices because it is simple and takes little memory. And, yes, TFTP software is also available for Windows CE H/PCs. If your access equipment supports FTP, you are still in business.
As with SNMP managers, Telnet and Web browsers must be running to receive unsolicited alarms. This presents a problem for mobile management because your computer will not be turned on all the time. For mobile management, unsolicited alarms must be stored in the network until you can retrieve them later. This is where another Internet mainstay, e-mail, comes in. E-mail servers allow alarms to be sent and stored for later retrieval. E-mail can ensure more timely response to alarms with the use of text pagers that have Internet e-mail addresses. When combined with Telnet or a Web browser, e-mail can provide a very effective mobile management capability. A properly implemented e-mail capability even supports notifying multiple people and trouble ticket logging. E-mail alerts from a WAN access device are far less prevalent than the use of embedded Web servers in those devices.
More and more equipment vendors are placing support information on the Web in FAQs, answering e-mails for support and sponsoring Internet news groups. All of these are available over an Internet connection from your PC, H/PC or other computing device. If you want to use the Internet for mobile management access, you will have to seek out network access products that support the full set of protocols you wish to use. The flexibility of management access from anywhere is a real winner even when used to augment classic enterprise SNMP managers.
Embrace mobile network management and someday you could be checking your e-mail over a wireless connection to your handheld while enjoying a large latte at your favorite Starbucks. You no longer need to be afraid to leave the office for lunch. Even better, an e-mail informs you before any of your users notice a problem. This beats problem notification the old way, perhaps by your manager- the loud career-limiting variety.
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