NSTL evaluates six programs that let you control your PC remotely
Remote-control programs are a special category of communications application. They go beyond just connecting with another computer to actually taking control of it. Connecting through phone lines and modems or through LAN connections, these programs can put all the resources of one PC, usually called the host, at the disposal of a remote user's computer. The local PC screen (the remote or viewer) duplicates the host PC's screen: The keyboard enters characters directly to the host PC, and the mouse moves the host PC's mouse pointer. The local screen constantly receives data from the host PC screen, detailing every change in status. Likewise, the keyboard sends data to the host PC every time a key is hit. For all practical purposes, the remote user may as well be sitti
ng in front of the host PC.
In the early days of remote-control software, most of us used these programs to access our office systems from home PCs. You could leave your office PC and modem on with the remote-control program running in host mode. You could then call in and take control from the home PC, perhaps running Excel to update a spreadsheet file or using Freelance Graphics to create charts. You could also transfer files from your office to your home PC. Companies could also provide technical support for PCs at remote sites via modem. Technicians could take control of a problem PC at a remote site, view the problem directly, and fix it without spending hours on the phone or traveling to the site.
A more recent use is to dial in (via modem) to a network-connected PC at the office, log in, and run network applications or update shared files on the network. Technical-support use of remote control has expanded to include connecting directly through the company LAN. Help-desk personnel on the
sixth floor of an office building can now use remote control through the network to fix a problem on an executive's PC on the eighteenth floor.
The Windows Connection
As Windows has grown in popularity, the demands made on remote-control communications have increased. A graphical interface such as Windows works with many times more screen data than older DOS interface programs--screen data that has to travel continuously over a relatively slow modem connection. Even with the faster modems now available, the response time for Windows applications over remote-control connections was not acceptable until remote-control programs written specifically for Windows emerged.
This report evaluates the six remote-control programs most widely used for running Windows applications. Carbon Copy for Windows, CoSession for Windows, Norton pcAnywhere for Windows, and ReachOut Remote Control are Windows applications that have taken over from previous DOS-based versions. Remotely Possible was introduced orig
inally in Windows form. Close-Up is the sole DOS application we tested. Even though it is not Windows-based, it runs Windows applications and is positioned in direct competition with the other programs. For this issue, we did not consider programs that do not connect via modem.
Smart Screen Refresh
The bottleneck caused by modems can have a significant effect on the speed of remote-control operations. For the LAN versions of these programs, performance would be affected by the speed of a session link between two LAN workstations rather than a modem; however, since networks are many times faster than modems, this review concentrates on performance of remote control via modems.
To boost performance, remote-control programs try to minimize the amount of data that needs to be transmitted. In the past, remote control worked by sending and refreshing the entire image of the host PC's screen to the remote PC every fraction of a second. The constant rate at which the screen images were sent to the
remote PC was called the screen refresh rate. The remote PC's screen accurately reflected the host PC's screen as changes at the host PC would be included in the next screen refresh.
Many times, a change is limited to a small section of the screen (e.g., moving the mouse pointer an inch, pulling down a menu, or highlighting an object), and only the changed data needs to be refreshed. The remote system can use the screen data it already has and just refresh the unchanged parts of the screen. By cutting out redundant screen-refresh data, a remote-control program can greatly increase the response time.
Smart screen refresh is implemented in one form or another in Close-Up, CoSession, pcAnywhere, ReachOut Remote Control, and Remotely Possible. It is not a standardized feature, which is to say that some of the programs appear to filter out more redundant screen data than do others.
Caches speed the performance of hard drives and memory chips, and they also work well for remote-control program
s. The idea behind a cache is to keep recently used data in a temporary storage area that is quickly accessible. If the data is soon needed again, it is much quicker to access it from the fast-access temporary storage area than to retrieve it from the original source. So, elements of a recently displayed screen are saved as a cache in extended memory. If the remote user returns to a recently displayed screen, the entire page redraws from the remote PC's screen cache, eliminating the need to transfer large amounts of data over the modem from the host. Screen elements that are often redrawn from a screen cache include bit maps, text, and fonts.
All the tested programs use caching to boost performance, although the effectiveness of the caching algorithms differs. The Page Redisplay performance test is a good example of a screen cache being employed to redraw a screen. Close-Up's Photographic Memory caching is especially effective.
Efficient Communication
Data transfer via modem is regulated b
y a communications protocol, which is a method for breaking the data stream into small packets and checking that each packet arrives intact. If a packet does not arrive intact (e.g., noise on the phone lines sometimes corrupts an individual packet), the protocol interrupts the data flow and resends the damaged packet.
Each of the remote-control programs tested uses a proprietary transfer protocol, and the efficiency of the protocol has a significant effect on the speed of data transfers between modems. Packet size and error-checking methods can speed or slow data transfers, depending on how they are set. Larger packets, for example, provide better performance when there is little noise on the phone lines, because the protocol need not resend corrupted incoming packets. But they hurt performance when there are higher levels of noise on the phone lines, because the larger packets take more time to be retransmitted. Some protocols pause as each packet is checked; others do not pause, or pause less often,
allowing an almost continuous transmission and providing significantly better performance. Again, with noisy phone-line conditions, this method can actually hurt performance.
Another feature employed to improve performance, specifically during file transfers, is to compress files as they are sent and uncompress them at the receiving system. Depending on the level of compression that can be attained, the time saved overall is more than worth the time it takes to compress and decompress the file. Carbon Copy, Close-Up, CoSession, pcAnywhere, and ReachOut Remote Control all use file compression.
If the file will not compress, the time spent trying to compress it is wasted and slows performance. NSTL's File Transfer performance test illustrates this point. In this test, a compressed file is transferred twice, once with file compression enabled and another time with it disabled. Carbon Copy, pcAnywhere, and ReachOut all have faster times with the feature disabled. CoSession and Close-Up appear able
to turn off compression when transferring a compressed file and so achieve the same time for both tests.
Remotely Possible doesn't compress files, but it benefits from external compression because the V-series v.42 modems we use for testing compress data automatically. Modem compression, however, generally doesn't match software compression.
Resolving Resolutions
When a remote user connects to a host PC, the assumption is that the screen data from the host PC will exactly fit in the screen of the remote PC. That assumption will be challenged if both screens are not at the same resolution. With Windows supporting resolutions of up to 1280 by 1024 pixels, one system may well be running in a higher resolution than the other. Most of the programs support a variety of SVGA resolutions (Close-Up supports up to only 800 by 600 pixels), and all allow PCs with differing screen resolutions to connect.
The programs handle different screen resolutions in several ways. Where the remote PC is at
the higher resolution, the host PC's entire screen fits into a small window on the remote screen. If the remote PC is at the lower resolution, the host's screen will be too big for the remote's screen. The remote then displays one area of the host's screen, and you access the rest by scroll bars, mouse, or arrow keys. Close-Up takes a unique approach, forcing the higher-resolution PC to drop to the resolution level of the other PC. The other programs take approaches that are reasonably similar to each other. ReachOut, pcAnywhere, and CoSession have scroll bars for moving around the host screen; Remotely Possible uses the mouse and arrow keys. Carbon Copy brings up a small box to represent the other screen.
Security
User passwords and a master password for the host PC are good precautions against unauthorized access. User passwords are individual passwords that remote users must enter during the initial connection to the host. The master password limits access to the screen where all the other use
r passwords are edited. Without a master password, anyone with a user password could open the password table and memorize or change the other individual passwords. All six programs support both user passwords and a master password.
Automatic dial-backs are the next level of protection. A dial-back number is associated with each log-in name and password. When someone logs in, the call is disconnected and the host calls back at the designated callback number. This keeps an unauthorized user with someone else's password from connecting unless the call is made from the legitimate password holder's phone (where the callback is received). The dial-back feature should not be confused with a roving callback, which will call the remote user at any number. Roving callback is a convenience feature primarily used to reverse long-distance charges incurred during a modem connection. All six programs support automatic dial-backs; Carbon Copy, Close-Up, pcAnywhere, and ReachOut Remote Control support roving callbacks.
Encryption is probably the ultimate level of security. Users worried about phone-line tapping or eavesdropping should choose a program with the ability to encrypt the log-in password upon log-in, or even all the data during the connection. A line tap would be able to intercept only gibberish, because it would not have the encryption key needed to translate the gibberish back into meaningful data. All the programs except pcAnywhere support password encryption. Data encryption is supported by CoSession, ReachOut Remote Control, and Remotely Possible, but because of strict federal regulation of data encryption products, users should arrange with their software dealer to make sure it is included with their purchase.
Remote-Control Choices
Close-Up, with support for more than 600 modems, includes more than three times the drivers of any other program. It provides excellent performance when redisplaying a screen on the remote system, thanks to its built-in Photographic Memory caching. Users wil
l find this especially useful when moving through a multipage document. Usability is hampered by the absence of on-line help throughout most of the program and the lack of icons and windows such as the other programs offer. Close-Up is notable for its ability to work with third-party virus-checking programs.
CoSession is a strong program in nearly every category. Its speed is quite good, particularly in file transfer and video display tests--two important performance categories. CoSession's feature set is extensive, and it will operate at a DTE rate of 230.4 Kbps, one of only two tested programs to do so. It has excellent on-line help, but some aspects of the program are difficult to learn.
No other program matches the all-around excellence of ReachOut Remote Control. It delivers in almost every category, with the fastest overall performance, the highest usability rating, and the most features. Testers unanimously rate it number one in the general usability evaluation. ReachOut also offers a bui
lt-in virus checker. With its optimal mix of performance and power, ReachOut should handily meet any remote-control needs.
The Facts
Carbon Copy for Windows 2.0
Modem and LAN combined..............$199
Microcom, Inc.
500 River Ridge Dr.
Norwood, MA 02062
(617) 551-1000
Close-Up 6.0
Modem $199
2-user LAN..........................$395
8-user LAN..........................$795
Norton-Lambert Corp.
P.O. Box 4085
Santa Barbara, CA 93140
(805) 964-6767
CoSession for Windows 1.0c
Modem...............................$199
LAN (up to 25 workstations).........$295
Triton
200 Middlesex Tnpk.
Iselin, NJ
08830
(800) 322-9440
(908) 855-9440
Norton pcAnywhere 1.0
Modem and LAN combined..............$199
Symantec Corp.
10201 Torre Ave.
Cupertino, CA 95014
(408) 253-9600
ReachOut Remote Control 4.0
Modem...............................$199
4-user LAN..........................$295
1-user add-on.......................$195
10-user add-on......................$250
Ocean Isle Software
1201 19th Place
Vero Beach, FL 32960
(407) 770-4777
Remotely Possible/Dial 4.0e
Modem...............................$199
LAN (unlimited users at one site)...$499
Avalan Technology, Inc.
P.O. Box 6888
116 Hopping Brook Pk.
Holliston, MA 01746
(508) 429-6482
Overview
NSTL RATING VERSION
**** ReachOut Remote Control 4.0
*** CoSession for Windows 1.0c
*** Close-Up 6.0
*** Norton pcAnywhere for Windows 1.0
***
Carbon Copy for Windows 2.0
** Remotely Possible/Dial 4.0e
VERSION VERSATILITY QUALITY EASE OF LEARNING
ReachOut Remote Control 4.0 # # #
CoSession for Windows 1.0c # # #
Close-Up 6.0 # # #
Norton pcAnywhere for Windows 1.0 ## # #
Carbon Copy for Windows 2.0 ## ## #
Remotely Possible/Dial 4.0e ## # #
VERSION EASE OF USE PERFORMANCE PRICE
ReachOut Remote Control 4.0 # # $199
CoSession for Windows 1.0c # # $199
Close-Up 6.0 # # $199
Norton pcAnywhere for Windows 1.0 # # $199
Carbon Copy for Windows 2.0 #
# $199
Remotely Possible/Dial 4.0e ## # $199
KEY
Outstanding ***** Good #
Excellent **** Fair ##
Average *** Unacceptable ###
Below average **
Poor *
Highlights
Strengths
Carbon Copy Very easy to learn
Excellent manual
Automatic disconnect-after-transfer option
Close-Up Fastest page redisplay
Fastest remote printing
No modification of system.ini and win.ini files
CoSession Drive redirection
Fastest transfer of graphics file
Fast video display
Norton pcAnywhere Fastest overall file transfer times
Largest number of programming features
Best on-line help system
ReachOut Remote Control Fastest program overall
Most versatile program
No modification of system.ini and win.ini files
Remotely Possible/Dial Best quality overall
Bidirectional file transfer
Fastest transfer of compressed files
Limitations
Carbon Copy No remote printing
No inactivity disconnect
Limited choices for conditional file transfers
Close-Up Very limited on-line help
No background file transfers
No support of SVGA resolutions over 800 600 pixels
CoSession Setup features somewhat difficult
Slowest remote printing
Norton pcAnywhere Slowest page-redisplay times
No utility for modem customization
No password encryption
ReachOut Remote Control No message on a connection loss
Limited script programming
Remotely Possible/Dial Lowest overall usability
No programming features
Slowest performance overall
Illustration: ReachOut Remote Control, the top-rated program in the roundup, offers a strong set of features, including security options. ReachOut supports password protection, automatic dial-back, reboot on disconnect, and encryption.
Table: REMOTE-CONTROL COMPARISONS (This table is not available electronically. Please see September, 1994, issue.)
Illustration: Graph: REMOTE-CONTROL PERFORMANCE
We tested performance of the remote-control programs using Compaq ProLinea 4/25s systems as the host and remote. The systems were equipped with 8 MB of RAM, DOS 6.2, and Windows 3.1. For the
file transfer tests, we transmitted four different file types, because transfer speed can be greatly affected by how well the transfer protocol and compression algorithm match with the format of the file being transferred. We used a two-page Word for Windows 6.0 document for the Remote Printing and Page Redisplay tests. The Video Display tests measure the programs' speed displaying a series of (mostly) graphical files. We made every effort during the testing to optimize the performance of these programs. We conducted the tests at DTE speeds of 9600 bps and 57.6 Kbps. All times are in seconds; shorter bars indicate better performance.
Illustration: CoSession is a very strong program in nearly every category. Its speed is quite good, particularly in file transfer and video display tests, two very important performance categories. CoSession's feature set is extensive, and it will operate at a DTE rate of 230.4 Kbps, one of only two tested programs to do so. Some aspects of the program are dif
ficult to learn.
Remote-Control Windows
