Getting more from broadband 5: Remote working

Why not put your broadband connection to good use by freeing up some of your time and working from home?

Remote control
High speed and good reliability make broadband connections viable for remote working, freeing you from the tyranny of office life. However, there are some precautions that need to be observed.

Before considering using a virtual private network (VPN), you should establish the security of your PC and home network. Once connected to your company VPN, your PC is typically treated as if it were a station on the office local area network (Lan).

This means that the connection between your PC and others isn't firewalled as normal internet traffic would be. Should your PC be compromised over the internet, a VPN connection and its privileged status would provide the ideal starting point for attacks on internal systems. This is how Microsoft had its source code accessed recently.

VPN latency
The performance of broadband connections - while being fast enough for web surfing and general use - is still much lower than the performance of a typical office Lan. A good DSL connection offers 1Mbps downstream and 128Kbps upstream; a modern office Lan offers 100Mbps.

Also, VPN latency is much higher. Machines on a VPN might be logically close together, but the number of routers ('hops'), through which each packet must pass, and the overhead of VPN processing at either end mean packets between apparently adjacent VPN stations have latencies of hundreds of milliseconds, rather than the 1ms to 10ms of a Fast Ethernet Lan.

Also, the asymmetric nature of ADSL and most cable modem connections is a problem - when saving or searching data, there's a much higher proportion of outbound traffic than when web surfing, which forms a bottleneck.

You shouldn't expect a VPN connection over DSL or a cable modem to be as flexible as a Lan. Mapping network drives and performing searches that look through files on remote servers both invite sluggish performance that'll saturate the VPN connection and render it unusable while traffic-heavy operations are completed.

To avoid these problems, save files locally and occasionally synchronise. With Windows, the Briefcase feature, originally intended for on-the-road notebooks, can be useful to synchronise local and network storage and avoid long latencies while editing.

Windows 2000 and later include support for VPNs. Only Windows XP Professional, however, offers easy-to-use support for IP Security (IPSec) based VPNs. Earlier versions of Windows require third-party clients for easy connections. VPN support in Linux is complete, but not as easy to configure.

FreeS/Wan is the platform of choice for IPSec support and Microsoft PPTP (used by the Windows 2000 VPN client) support is available using PoPToP. However, getting a working system incorporating IPSec and Microsoft's Point-to-Point Tunneling Protocol with full encryption requires a variety of kernel patches and isn't an easy task.

SSH
Remote control utilities provide another means of working. Unix/Linux have always offered remote login and system management facilities via telnet, login and secure shell (SSH). These allow you to log in to a remote system as if at the console and browse/execute commands in text mode. Telnet and login are insecure; these days SSH is preferred.

Many users can log in simultaneously from different locations, exploiting the multiuser nature of Unix. Modern Linux distributions include SSH server and clients. Windows isn't multiuser out of the box - Terminal Services offers the ability for multiple users to run programs with remote display, but at an additional cost.

Besides text-mode logins, several mechanisms exist for displaying remote desktops or individual remote programs. X-Windows on Unix/Linux allows for easy remote display of windows, however it's bandwidth hungry. More modern and efficient solutions offering similar functionality are Citrix ICA and VNC.

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