NetTEL 2520/2500, PoPToP
You configure and maintain the NetTEL through a slick web-based user interface, although the router ships without an assigned IP address which makes accessing those pages somewhat difficult to start. Before you can configure anything, you must assign the NetTEL an IP address on your network. Since you cannot connect a keyboard, monitor or serial console to the NetTEL, you need a working LAN with at least one computer on it to convince the NetTEL to do more than flash its lights dolefully.
The good news is you don't need to find a Windows machine or run any NetTEL-specific software to assign the NetTEL its address. You can use a standard DHCP server on Linux or Windows. Needless to say, this is going to be a problem for some users. If you already have enough of a network to be running a DHCP server, your network is probably enough that you don't need the NetTEL. On the bright side, setting up a DHCP server is less work than duplicating the features of the NetTEL, so it is still a fair trade. If you have a Windows machine around, an install wizard will transfer the spark of life to the NetTEL in minutes.
Once an IP address has been assigned, configuring the NetTEL is easy. Bring up your web browser, enter the IP address, and a nicely designed web page will guide you through setting up the Internet connection type, creating dial-in and VPN connections, dial-out Internet connections, configuring the internal DHCP server, security filtering, etc. If you are using the NetTEL for dial-up Internet access, you can configure it to remain connected all the time or automatically establish a dial-up connection whenever you go to access the Net. The configuration options are explained well on the web page, and the manual includes item-by-item instructions for each configuration page.
If you already have a DHCP server or use the Windows software, the complete installation and configuration can take less than 20 minutes.
In operation, the NetTEL usually does exactly what a router should—disappears into the background. It does its job, and you don't have to worry about it. If you do run into trouble, there are diagnostic tools available on the NetTEL's built-in web page. You can even set up the NetTEL to log error and status messages to your Linux machine using syslog, eliminating the need to check the web page for error messages.
When talking about network equipment, reliability is king. One of the strongest advantages of the NetTEL is the inherent reliability of its compact, solid-state design. No hard drive to trash, no fan to stop spinning, no keyboard to spill Coke on and no monitor to drop on your foot. It just silently does its job, and that's something very hard for a PC-based solution to compete with. I had no problems with the NetTEL hardware.
Moreton Bay put some thought into field-upgrading the NetTEL, too. The firmware can be upgraded using either tftp to a Linux machine or by using a Windows utility that is probably just a smart tftp server. Upgrading the firmware from a Linux box can be as simple as clicking a button on the web page. After an upgrade, the NetTEL will remember your old configuration options if possible.
It is all very fine to talk about sharing a single Internet connection, but sharing means slow, right? Not always, as I found out. I was amazed to see about a 20% throughput improvement with the NetTEL over dialing directly from my Linux desktop computer to access the Web. Fast serial ports and a dedicated CPU can truly help network performance. I didn't notice any improvement when using the 2520's second Ethernet connection to access the Internet like an ADSL or cable connection, but I didn't see a noticeable slowdown, either.
Not everything is rosy. The NetTEL does its job very nicely, but the job it does comes with some limitations. When using the NAT feature to share a single IP address, the NetTEL acts as a rigid firewall, blocking all incoming connections to your computers. This is normally a good thing, but not all network applications will work when you cannot make an incoming connection to the client computer. Unfortunately, there is no guaranteed workaround for those programs, and there is no way around the NAT feature when using the NetTEL to connect to the Internet.
The VPN feature provides the workaround for NAT's obstinate blocking of incoming packets, in some cases. If you know you will need to interact with a particular machine outside your physical network, you can set up a VPN link to bring that machine into your virtual network. Unfortunately, that works only for people you know and machines you or they control.
If you use the dial-on-demand feature, the NetTEL automatically connects to your ISP whenever you go to bring up a web page or run an Internet application like TELNET, but it isn't very selective about what programs cause it to dial. If you have software that periodically tries to make a connection to a remote host, such as a network time server, your dial-up connection will either stay up 24 hours a day or connect at seemingly random times. I had been testing the NetTEL for about three weeks when I got an e-mail from my ISP saying that perhaps I should lay off the caffeine because I was constantly dialing, staying on-line for fifteen minutes, and disconnecting for another five, only to dial back up again. I traced that back to xntpd running on one of my Linux boxes, but I've seen the same interaction from several other programs, most of them Windows applications. If you are unfamiliar with tcpdump or some other network monitoring tool, tracking down unsolicited dialing can be a bit of a trick.
I also had a minor problem with the modem I used to test the NetTEL's dial-up networking support. The NetTEL's modem initialization script is very generic, but wasn't able to reset the modem and place a call. That's where the NetTEL's Linux core appeals to anyone familiar with Linux networking. A minor change to the same chat script you'd find on a full Linux PC, and everything was working great.
In the end, these problems are just proof that there are no magic bullets—they are almost all unavoidable side effects of the good features of the NetTEL.