Linksys WRT54G Ultimate Hacking

Using Third-Party Firmware • Chapter 3 141

Configuring and Using DD-WRT

Your primary interface to DD-WRT will be the Web interface. It allows you to configure many of

the useful features offered by DD-WRT and is more enhanced than its OpenWrt counterpart. For

this reason, many novice users will prefer DD-WRT. In addition to the Web interface, you can still

use the command line to make changes; however, be certain to read the documentation as the com-

mand-line interface for DD-WRT is not as full-featured or well documented as the OpenWrt com-

mand line. We provide a few examples of DD-WRT configuration so that you can get a feel for the

interface. This will enable you to configure other options by exploring the Web interface and DD-

WRT documentation (located at www.dd-wrt.com).

Setting the Wireless Radio Transmit Power

Not only does DD-WRT allow you to change the transmit power of the radio, but it also offers the

ability to graphically view and change these settings (see Figure 3.4).

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142 Chapter 3

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Using Third-Party Firmware

The setting most users are typically interested in is about one-third of the way down, and labeled

"Xmit Power", which corresponds to the transmit power of the radio measured in milliwatts (mW).

You might be looking at the screen in Figure 3.4 and wondering what Afterburner is. No, we are

not talking about the video game, but about wireless chipset manufacturers attempt to get more

throughput using 802.1 lg. Broadcom's attempt was marketed to device manufacturers as

"Afterburner" and rebranded by Linksys as "SpeedBooster". It uses a combination of reduced signal

overhead and combining packets to provide more throughput. Of course, this does nothing to

improve distance and the client card must also support this technology to see any performance

improvements (in fact, using it with cards that do not support it can decrease performance!). Linksys

originally intended that the WRT54GS models would only support SpeedBooster; however, third-

party firmware can enable this on even WRT54G models because the same chipsets are used. See

www.dd-wrt.com/wiki/index.php/Afterburner for more information.

Making the File System Writable

DD-WRT, by default, comes with the SQUASHFS file system enabled, so, unlike old versions of

OpenW1KT, you do not have to choose a file system at installation time.You can enable the writable

JFFS2 file system by going to the command line and changing the NVRAM variables.You can get to

the command line on DD-WRT by using Telnet. Later, we will show you how to enable SSH. To

enable JFFS2, do the following:

# nvram set j ffs_mounted=l

# nvram set enable_jffs2=l

# nvram set sys_enable_jffs2=l

# nvram set clean_jffs2=l

# nvram set sys_clean_jffs2=l

# nvram commit

# reboot

.... ~

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This works only on devices that have

4MB of flash or

more.

.... ~:

Working with VLANs

DD-WRT provides a nice interface for changing VLANs on selected ports, and even creating new

VLANs (see Figure 3.5).