kern/97306: NG_L2TP locks after connection with failed authentication

[Arcadiy Ivanov]

>Number:         97306
>Category:       kern
>Synopsis:       NG_L2TP locks after connection with failed authentication
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon May 15 15:20:19 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Arcadiy Ivanov
>Release:        6.1-RELEASE
>Organization:
>Environment:
FreeBSD fw1.home.ivanovy.net 6.1-RELEASE FreeBSD 6.1-RELEASE #1: Sat May 13 05:05:32 EDT 2006     administrator at fw1.home.ivanovy.net:/usr/obj/usr/src/sys/FIREWALL  i386

>Description:
I'm trying to setup sl2tps for Windows L2TP/IPSec connections. I after IPSec connection is established the L2TP connection is established, attempt to authenticate occurs, fails, L2TP connection is destroyed, IPSec connection is destroyed - all normal operations. 
Alas, next connection attempt results in the following sequence: IPSec connection is established, L2TP connection timesout, IPSec connection destroyed. Restarting sl2tps does not help (=> no port problem). Attempt to kldunload ng_l2tp after killing sl2tps results in "Device is busy." reply and there is absolutely no way to unload ng_l2tp kernel module at this point. The only solution is to restart the entire machine.
>How-To-Repeat:
Configure IPSec with PSK (for ease of configuration). Configure sl2tps with no users, try connecting from Windows XP box with MSCHAPv2 auth and any credentials more than one time (some times second or third connection will still work, but eventually ng_l2tp locks up).
>Fix:
None
>Release-Note:
>Audit-Trail:
>Unformatted: