Looks like you are loading a lua module built against a different version of lua.

On Nov 21, 2014, at 9:59 AM, 彭勇 <ppyy@pubyun.com> wrote:

freeswitch@internal> 2014-11-21 22:57:35.379103 [ERR] mod_lua.cpp:203 error loading module 'socket.core' from file '/usr/lib/lua/5.1/socket/core.so': /usr/lib/lua/5.1/socket/core.so: undefined symbol: luaL_prepbuffer stack traceback: [C]: in ? [C]: in function 'require' /tmp/t.lua:1: in main chunk

# cat /tmp/t.lua require "socket.core" local t =require('socket').tcp

-- Peng Yong