uHTTPd Web Server Configuration

The /etc/config/uhttpd configuration is provided by the uhttpd web server package. This file defines the behavior 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, php7, 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.

For information on sections and UCI configuration see The UCI System

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

config 'uhttpd' 'main'
        option 'listen_http' '80'
        option 'home'        '/www'

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.

As specified in the The UCI System documentation, each of the uhttpd sections must be named differently.

config 'uhttpd' 'main'
        option 'listen_http' '80'
        option 'home'        '/www'
 
config 'uhttpd' 'other'
        option 'listen_http' '8080'
        option 'home'        '/www/other'

In order to speak HTTPS/TLS, uhttpd needs one of several cryptographic libraries. Such libuhttpd-... packages can be installed via opkg, e.g. libuhttpd-mbedtls, libuhttpd-openssl or libuhttpd-wolfssl.

In the server configuration, the listen_https option needs to be defined as explained above.

uhttpd requires an X.509 certificate and a private key. You can create and copy them manually to the place specified in the configuration.

There is an alternative: 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 self signed certificate 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.

If you are hosting the website to internet you may want to obtain LetsEncrypt certificates.

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, crypt(1) 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:

# 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.

Example:

/etc/httpd.conf

/dashboard/:admin:$1$$ysVNzQc4CTMkp5daOdZ.3/
/:root:$p$root
/:alice:P@$$w0rd

• Here the /dashboard/ path is protected but allowed for user admin with the password secret that is hashed with crypt(1) MD5.
• The root path / is allowd to the user root and it's password will be taken from /etc/passwd
• Also the / path is allowed for the user alice and shes password is P@$$w0rd which is not hashed and stored in clear text.

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 php7 installation includes:

• php7
• php7-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:

list interpreter ".php=/usr/bin/php-cgi"

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
192.168.1.1

Then edit /etc/config/uhttpd and bind listen_http to specific 192.168.1.1 IP instead of 0.0.0.0 and comment out IPv6 bindings:

config uhttpd main
        # HTTP listen addresses, multiple allowed
        list listen_http        192.168.1.1:80
#       list listen_http        [::]:80
 
        # HTTPS listen addresses, multiple allowed
        list listen_https       192.168.1.1:443
#       list listen_https       [::]:443

See Accessing LuCI web interface securely for more details.

uHTTPd supports running Lua in-process, which can speed up Lua CGI scripts. Also LuCI works fine 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:

# 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.
# uci set uhttpd.main.lua_prefix=/lua
# uci set uhttpd.main.lua_handler=/root/test.lua
# 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
# /etc/init.d/uhttpd restart
# wget -qO- http://127.0.0.1/lua/
Hello world.

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:

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:

/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.