You're working on a network and trying to find a device, but can't remember the IP address and you don't have NMAP handy...This is particularly significant when dealing with network printers, etc. 

The two useful sequences are:

1. You may try pinging your network from a computer connected to the network, and lookup an arp table. On your computer, click [Start] -> [Run...] and type "cmd" and [Enter]. Type "ipconfig" to find your network address. The network address is found by performing a logical AND operation on your IP address and the subnet mask. For example, if your IP is 192.168.1.101 and subnet mask is 255.255.255.0, then the network address is 192.168.1.0. Ping your network using a broadcast address, i.e. "ping 192.168.1.255". After that, perform "arp -a" to determine all the computing devices connected to the network. One of the IP found will be your missing device.

2. You may also use "netstat -r" command to find an IP address of all network routes. However, if your device has problem communicating with other network devices, you may not be able to find IP address of the printer using "netstat" command.

Since I need to find this once a month or so...I've replicated it here...

Original located at http://www.dslreports.com/forum/remark,11490618~mode=flat

Well, I've managed to actually get Port Forwarding and other features working with the Speedsteam 5200 E242.

Here they are again:

Step 1: you have to make sure your IP is set to 192.168.2.2
Step 2: Go to »192.168.2.1/pfwizardj.cgi?code=E···retain=f and set "All Items" under "Profile Configuration Access" click next and choose "Do not require admin login"
Step2: Go to »192.168.2.1/pfwizardj.cgi?code=E···retain=f and do the same thing, except type 192.168.2.2 as your "Constant Profile IP Address".

(if everything went ok, you should now see the new configuration page)

From here, you have to access every configuration page manually. I've managed to figure out what some of them are, (plus the ones francoisr mentioned in another post.)

Here they are:

»192.168.2.1/dhcpcfg.htm - DHCP
»192.168.2.1/ddnscfg.htm - Dynamic DNS (what francoisr wanted)
»192.168.2.1/ipp_config.htm - IP Passthru
»192.168.2.1/updatelocal.htm - Update firmware
»192.168.2.1/ras_config.htm - RAS config
»192.168.2.1/naptcfg.htm - Port forwarding
»192.168.2.1/dmzcfg.htm - DMZ Config
»192.168.2.1/fwcfg.html - Firewall Config
»192.168.2.1/natcfg.htm - NAT/NAPT Configuration
»192.168.2.1/hostcfg.html - Host Configuration
»192.168.2.1/upnpcfg.html - UPNP Configuration
»192.168.2.1/ripcfg.html - RIP Configuration

I really hope these steps work for you guys, they surely worked for me.

I forward ports to 192.168.2.3, which is used on my main computer. If I wan't to change some settings, or forward some ports, I just switch to 192.168.2.2 and access the web interface again.