WP-SMF-Bridge is a simple user registration and logon bridge between WordPress and Simple Machine Forum. To get this working, it is highly recommended that you have a fresh, unmodified install of SMF 1.1 or higher installed and running alongside an install of WordPress. It must be installed in a subdirectory under your WP install and should not be being accessed through a sumdomain. For example, if your website’s address is mysite.mydomain.com, your forums should be somewhere like mysite.mydomain.com/myforum. Also, WordPress must be able to access your SMF configuration files, otherwise it won’t work!
Please do keep in mind that this is a new plugin, and has not been thoroughly tested yet – and should probably not be used on a production website! I am not responsible for any data loss that might occur through your use of this plugin! Please see the plugin’s website for a bug-tracker and bug reporting system! If you find a problem, let me know about it so that it may be fixed. If you want to see a feature added, let me know about it so that I may add it!

SMF Bridge

User registration and login bridge between Wordpress and Simple Machine Forum

x0DSR

WP2SMFBridge is a simple one way bridge from WordPress to Simple Machine Forum (v2 tested). This means, this one uses databases of SMF Forum and sync to WP database every time a user performs login or logout action in WP. To get this working only use WP to register/login/logout. Also, WP and SMF must be installed in same domain, and should not be being accessed through a subdomain, though it still work. For example, if your website contains of WordPress for news and SMF for forum, if your news is mydomain.com, then your forums should be somewhere like mydomain.com/forum.
This plugin will do these following tasks:
<ul>
<li>If a user log in WP, then that user will be logged in SMF.</li>
<li>If a user logout in WP, then that user will be logout in SMF.</li>
<li>If a user created/register/change password in WP, those actions happen on SMF!</li>
<li>Users that are created in SMF can be used once disabled WP plugin.</li>
<li>For a full way integration use with SMF2WPBridge plugin. 
https://github.com/xchwarze/SMF2WPBridge 
http://custom.simplemachines.org/mods/index.php?mod=4030</li>
</ul>
<h3>Notes</h3>
Every time a user logged in SMF forum, same username (will be created if not exist) will be logged in WordPress. Because SMF is placed in higher order, so user in WordPress will be changed to SMF with same role.
For example, you have an administrator named “admin” in wordpress, after WP2SMFBridge fully activated, the SMF user named “admin” can login as that administrator. So be careful!

WP2SMFBridge

Login bridge from Wordpress to Simple Machine Forum.

SMF Bridge vs WP2SMFBridge