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ntlm: Nginx ntlm module implemented by lua


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CentOS/RHEL 7 or Amazon Linux 2

yum -y install
yum -y install lua-resty-ntlm

CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023

yum -y install
yum -y install lua5.1-resty-ntlm

To use this Lua library with NGINX, ensure that nginx-module-lua is installed.

This document describes lua-resty-ntlm v0.2 released on Feb 07 2018.

Windows authentication is always used inside company. IIS can enable Windows authentication easily. For Nginx users, some solutions aren't friendly: Nginx Pro provides ntlm module but it isn't free; reverse proxy must setup other server firstly.

The project is inspired by express-ntlm and PyAuthenNTLM2. IIS will trigger windows authentication scenario for each connection. Unlike IIS, the project only trigger ntlm for first requestion. After authentication done, http header Authorization:Bearer will be sent to browser, and browser should put it in each request package to avoid ntlm again. At the same time, http header: X-Ntlm-Username and X-Ntlm-Domain will be sent to upstream.

NOTICE: don't set-cookie during ntlm authentication. (#1175)


  • install OpenResty which integrates Nginx and LuaJIT
  • intall LuaRocks because ntlm.lua depends on struct, iconv module
  • install struct module: sudo /usr/local/openresty/luajit/bin/luarocks install struct
  • install iconv module: sudo /usr/local/openresty/luajit/bin/luarocks install lua-iconv
  • save ntlm.lua into /usr/local/openresty/site/lualib
  • add the following code to /usr/local/openresty/nginx/conf/nginx.conf:
        lua_shared_dict ntlm_cache 10m;
        keepalive_timeout  35;
        ... ...
        access_by_lua_block {
            local cache = ngx.shared.ntlm_cache
            require('ntlm').negotiate("ldap://", cache, 10)
            -- cache is shared DICT
            -- timeout is less than keepalive
  • restart nginx service: sudo service openresty restart


You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-ntlm.