Hydra is a complete suite for PPTP.

Hydra1: Gets the PPTP passwords (PAP, MS-CHAP, MS-CHAP2).
        MS-CHAP passwords have to be cracked by L0phtCrack.
	Hint: To crack MS-CHAP and MAC-CHAP2 passwords that have no 
	      LANMAN hash, insert some dummy chars in the LANMAN password 
	      field (the first ""), because sometimes LC tries to crack first
	      the 00000000.... LANMAN hash.
	
Hydra2: Decapsulates PPTP connections. You can see tunnelled connections
        in the standard ettercap connection list, grab passwords and so on.
	You can't use hydra2 during arp-sniffing sessions.
	Hint: If you need to use hydra2 while arp-sniffing, launch a second
	      ettercap instance, select the tunnel destination (or the 
	      gateway) as DEST, leave blank the source, and then select
	      MAC-based sniffing.
	      Using Hydra5 in conjuction with Hydra2 is highly recommended 
	          
Hydra3: Forces re-negotiation on an existing tunnel. You have to use arp-sniff
        to launch hydra3. You can force re-negotiation for grabbing passwords
	already sent. Furthermore you can use hydra3 to perform hydra4, hydra5 
	and hydra6 operations on existing tunnels.
	
Hydra4: Forces PAP authentication during tunnel negotiation. It could fail
        if PAP is not supported, if pap_secret file is missing,
	or in case windows is configured with "authomatic use of domain 
	account". (It could fail even for many more reasons).
	You have to use it while arp sniffing. Useful with Hydra1.
	
Hydra5: Forces no compression\encryption for tunnels during negotiation.
        Very usefull with Hydra2. You have to use it while arp sniffing.
	It could fail if client (or the server) is configured to hang off 
	the tunnel if no encryption is negotiated.
	
Hydra6: Forces MS-CHAP from MS-CHAP2 during tunnel negotiation. MS-CHAP
	passwords are usually easier to crack than MS-CHAP2. 
	You have to use this while arp sniffing. It rarely fails because
	MS-CHAP is often supported for retro-compatibility in windows
	environment. Usefull with Hydra1. 
	
L2TP Hint: By default, windows machines try first the more secure L2TP 
           to estabilish a VPN tunnel. 
	   If ipsec exchange fails, windows rolls back on PPTP. 
	   So.....take a look even to the ROPER plugin :)
	   
	    	
