The /etc/config/uhttpd configuration is provided by the uhttpd web server package used since OpenWrt 10.03 (Backfire). This file defines the behaviour of the server and default values for certificates generated for SSL operation. uhttpd supports multiple instances (i.e. multiple listen ports, each with its own document root and other features) as well as cgi, php5, perl and lua.

There are two sections defined, the section of type uhttpd contains general server settings while the cert one defines the default values for SSL certificates.

A minimal uhttpd config section must consist of at least the document root and HTTP listen options:

The options defined for this section are outlined below.

Multiple sections if the type uhttpd may exist - the init script will launch one webserver instance per section.

First of all, you need to install the uhttpd-mod-tls package in order to pull into the system the 'TLS plugin which adds HTTPS support to uHTTPd'.

Then if listen_https is defined in the server configuration, the certificate and private key is missing. In this case (as of 10.03.1) you'll need to install the luci-ssl meta-package which in turn will pull also the px5g script. With this utility the init script will generate the appropriate certifcate and key files when the server is started for the first time, either by reboot or by manual restart.

The /etc/config/uhttpd file contains in the end a section detailing the certificate and key files creation parameters:

Those will be needed only once, at the next restart.

For backward compatibility reasons, uhttpd uses the old Busybox httpd config file /etc/httpd.conf to define authentication areas and the associated usernames and passwords. This configuration file is not in UCI format and usually shipped or generated by external packages like webif (X-Wrt).

Authentication realms are defined in the format prefix:username:password with one entry per line followed by a newline.

• prefix is the URL part covered by the realm, e.g. /cgi-bin to request basic auth for any CGI program
• username specifies the username a client has to login with
• password defines the secret password required to authenticate

The password can be either in plain text format, MD5 encoded or in the form $p$user where user refers to an account in /etc/shadow or /etc/passwd.

A plain text password can be converted to MD5 encoding by using the -m switch of the uhttpd executable:

root@OpenWrt:~# uhttpd -m secret
$1$$ysVNzQc4CTMkp5daOdZ.3/

If the $p$… format is used, uhttpd will compare the client provided password against the one stored in the shadow or passwd database.

Like Busybox HTTPd, the URL decoding of strings on the command line is supported through the -d switch:

root@OpenWrt:/# uhttpd -d "An%20URL%20encoded%20String%21%0a"
An URL encoded String!

A minimal php5 installation includes

• php5
• php5-cgi

In /etc/php.ini ensure that the doc_root is empty if you are using multiple uhttpd instances (each on its own port). This enables the uhttpd 'home' variable to work for you.

Ensure that you uncomment the extension interpreter line for PHP in the main section of the uHTTPd config file:

By default, uHTTPd is bind to 0.0.0.0 which also includes the WAN port of your router. To bind uHTTPd to the LAN port only you have to change the listen_http and listen_https options to your LAN IP address.

To get your current LAN IP address run this command:

uci get network.lan.ipaddr

uHTTPd supports running Lua in-process, which can speed up Lua CGI scripts. It is unclear whether LuCI supports running in this embedded interpreter. LuCI seems to work fine (if not better) with the embedded Lua interpreter. See the next subsection for instructions on how to set it up.

Here is an example using a test file test.lua to show it works:

root@OpenWrt:~# opkg install uhttpd-mod-lua
Installing uhttpd-mod-lua (18) to root...
Downloading http://downloads.openwrt.org/snapshots/trunk/ar71xx/packages/uhttpd-mod-lua_18_ar71xx.ipk.
Configuring uhttpd-mod-lua.
root@OpenWrt:~# uci set uhttpd.main.lua_prefix=/lua
root@OpenWrt:~# uci set uhttpd.main.lua_handler=/root/test.lua
root@OpenWrt:~# cat /root/test.lua
function handle_request(env)
        uhttpd.send("Status: 200 OK\r\n")
        uhttpd.send("Content-Type: text/plain\r\n\r\n")
        uhttpd.send("Hello world.\n")
end
root@OpenWrt:~# /etc/init.d/uhttpd restart
root@OpenWrt:~# wget -qO- http://127.0.0.1/lua/
Hello world.
root@OpenWrt:~#

Taken from http://pastebin.com/8H9eqiJ3. Tested on Backfire 10.03.1 with uHTTPd 28. Taken from http://pastebin.com/8H9eqiJ3 with minor fix to make it pass on Barrier Breaker. Tested on Barrier Breaker 14.07 with uHTTPd 2014-08-25.

You need to install uhttpd-mod-lua and luci-sgi-uhttpd to get it to work:

root@OpenWrt:~# opkg install uhttpd-mod-lua luci-sgi-uhttpd

In Chaos Calmer 15.05, the luci-sgi-uhttpd package is not needed. The appropriate files are included in luci-base.

Then uncomment the following lines in /etc/config/uhttpd (or add them if you don't have them):

        option lua_prefix       /luci
        option lua_handler      /usr/lib/lua/luci/sgi/uhttpd.lua

Then restart the server:

root@OpenWrt:~# /etc/init.d/uhttpd restart

One thing remains to be done. By default /www/index.html redirects you to /cgi-bin/luci which is the default CGI gateway for LuCI. The config above puts LuCI through embedded interpreter under /luci (lua_prefix is what causes it) so you have to change that in /www/index.html. The path appears there twice (one for the meta tag which does the redirect and one for the anchor). You can also copy/paste the code below if you don't want to meddle with it on your own.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="refresh" content="0; URL=/luci" />
</head>
<body style="background-color: black">
<a style="color: white; text-decoration: none" href="/luci">LuCI - Lua Configuration Interface</a>
</body>
</html>

Also remember to flush the browser's cache if you relied on the redirection because otherwise it will probably keep redirecting you to /cgi-bin/luci until the cache expires by itself.