Given: An embedded Linux computer with ethernet and wifi interfaces that can be configured using the traditional command-line tools such as ifconfig, iwconfig, wpa_supplicant, etc. This computer does not have a display or keyboard. You can log into it via ssh.

Question: Is there a tool for configuring the network interfaces that doesn't involve editing files? Something similar to a router browser-based interface or a command-line/curses based application.

I've tried wicd but the 1.7.2.4 release has some show-stopper bug in it which is known, supposedly fixed in the 1.7.3 version, but it appears that the project hasn't been maintained in a long time so 1.7.3 was never released.

I've also just tried webmin which is promising but the network module only works on a few flavors of Linux (I'm running Yocto) and I don't think there is wifi support in it.

Do you try MCM manager?
https://code.google.com/p/mcm-connections-manager/

That's not what I meant. I'm talking about ways to configure eth0, wlan0, etc. with IP addresses, gateway addresses, net masks, WPA supplicant SSID, password, etc. without having to manually edit /etc/network/interfaces and/or wpa_supplicant.conf. There are all manner of ways to do this in a desktop environment but for a faceless embedded system, I've only found the two I've mentioned.

If your focus is wireless on Yocto, Yocto support Connman for wireless and connman is CLI.