I have a problem with setup VPN server on my Ubuntu VPS, here is my server environments:

• Ubuntu Server 12.04 x86_64
• xl2tpd 1.3.1+dfsg-1
• pppd 2.4.5-5ubuntu1
• openswan 1:2.6.38-1~precise1

After install software and configuration:

ipsec verify

Checking your system to see if IPsec got installed and started correctly:
Version check and ipsec on-path                                 [OK]
Linux Openswan U2.6.38/K3.2.0-24-virtual (netkey)
Checking for IPsec support in kernel                            [OK]
 SAref kernel support                                           [N/A]
 NETKEY:  Testing XFRM related proc values                      [OK]
    [OK]
    [OK]
Checking that pluto is running                                  [OK]
 Pluto listening for IKE on udp 500                             [OK]
 Pluto listening for NAT-T on udp 4500                          [OK]
Checking for 'ip' command                                       [OK]
Checking /bin/sh is not /bin/dash                               [WARNING]
Checking for 'iptables' command                                 [OK]
Opportunistic Encryption Support                                [DISABLED]

/var/log/auth.log message:

Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [RFC 3947] method set to=115 
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike] meth=114, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-08] meth=113, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-07] meth=112, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-06] meth=111, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-05] meth=110, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-04] meth=109, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-03] meth=108, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-02] meth=107, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [draft-ietf-ipsec-nat-t-ike-02_n] meth=106, but already using method 115
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: ignoring Vendor ID payload [FRAGMENTATION 80000000]
Oct 16 06:50:54 vpn pluto[3963]: packet from [My IP Address]:2251: received Vendor ID payload [Dead Peer Detection]
Oct 16 06:50:54 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: responding to Main Mode from unknown peer [My IP Address]
Oct 16 06:50:54 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: transition from state STATE_MAIN_R0 to state STATE_MAIN_R1
Oct 16 06:50:54 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: STATE_MAIN_R1: sent MR1, expecting MI2
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: NAT-Traversal: Result using draft-ietf-ipsec-nat-t-ike (MacOS X): peer is NATed
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: transition from state STATE_MAIN_R1 to state STATE_MAIN_R2
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: STATE_MAIN_R2: sent MR2, expecting MI3
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: ignoring informational payload, type IPSEC_INITIAL_CONTACT msgid=00000000
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: Main mode peer ID is ID_IPV4_ADDR: '192.168.12.52'
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[5] [My IP Address] #5: switched from "L2TP-PSK-NAT" to "L2TP-PSK-NAT"
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: deleting connection "L2TP-PSK-NAT" instance with peer [My IP Address] {isakmp=#0/ipsec=#0}
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: transition from state STATE_MAIN_R2 to state STATE_MAIN_R3
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: new NAT mapping for #5, was [My IP Address]:2251, now [My IP Address]:2847
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: STATE_MAIN_R3: sent MR3, ISAKMP SA established {auth=OAKLEY_PRESHARED_KEY cipher=aes_256 prf=oakley_sha group=modp1024}
Oct 16 06:50:55 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: Dead Peer Detection (RFC 3706): enabled
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: the peer proposed: [My Server IP Address]/32:17/1701 -> 192.168.12.52/32:17/0
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: NAT-Traversal: received 2 NAT-OA. using first, ignoring others
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: responding to Quick Mode proposal {msgid:8579b1fb}
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6:     us: [My Server IP Address]<[My Server IP Address]>:17/1701
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6:   them: [My IP Address][192.168.12.52]:17/65280===192.168.12.52/32
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: transition from state STATE_QUICK_R0 to state STATE_QUICK_R1
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: STATE_QUICK_R1: sent QR1, inbound IPsec SA installed, expecting QI2
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: Dead Peer Detection (RFC 3706): enabled
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: transition from state STATE_QUICK_R1 to state STATE_QUICK_R2
Oct 16 06:50:56 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #6: STATE_QUICK_R2: IPsec SA established transport mode {ESP=>0x08bda158 <0x4920a374 xfrm=AES_256-HMAC_SHA1 NATOA=192.168.12.52 NATD=[My IP Address]:2847 DPD=enabled}
Oct 16 06:51:16 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: received Delete SA(0x08bda158) payload: deleting IPSEC State #6
Oct 16 06:51:16 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: ERROR: netlink XFRM_MSG_DELPOLICY response for flow eroute_connection delete included errno 2: No such file or directory
Oct 16 06:51:16 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: received and ignored informational message
Oct 16 06:51:16 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address] #5: received Delete SA payload: deleting ISAKMP State #5
Oct 16 06:51:16 vpn pluto[3963]: "L2TP-PSK-NAT"[6] [My IP Address]: deleting connection "L2TP-PSK-NAT" instance with peer [My IP Address] {isakmp=#0/ipsec=#0}
Oct 16 06:51:16 vpn pluto[3963]: packet from [My IP Address]:2847: received and ignored informational message

xl2tpd -D message:

xl2tpd[4289]: Enabling IPsec SAref processing for L2TP transport mode SAs
xl2tpd[4289]: IPsec SAref does not work with L2TP kernel mode yet, enabling forceuserspace=yes
xl2tpd[4289]: setsockopt recvref[30]: Protocol not available
xl2tpd[4289]: This binary does not support kernel L2TP.
xl2tpd[4289]: xl2tpd version xl2tpd-1.3.1 started on vpn.netools.me PID:4289
xl2tpd[4289]: Written by Mark Spencer, Copyright (C) 1998, Adtran, Inc.
xl2tpd[4289]: Forked by Scott Balmos and David Stipp, (C) 2001
xl2tpd[4289]: Inherited by Jeff McAdams, (C) 2002
xl2tpd[4289]: Forked again by Xelerance (www.xelerance.com) (C) 2006
xl2tpd[4289]: Listening on IP address [My Server IP Address], port 1701

Then it just stopped here, and have no any response.

I can't connect VPN on my mac client, the /var/log/system.log message:

Oct 16 15:17:36 azone-iMac.local configd[17]: SCNC: start, triggered by SystemUIServer, type L2TP, status 0
Oct 16 15:17:36 azone-iMac.local pppd[3799]: pppd 2.4.2 (Apple version 596.13) started by azone, uid 501
Oct 16 15:17:38 azone-iMac.local pppd[3799]: L2TP connecting to server 'vpn.netools.me' ([My Server IP Address])...
Oct 16 15:17:38 azone-iMac.local pppd[3799]: IPSec connection started
Oct 16 15:17:38 azone-iMac.local racoon[359]: Connecting.
Oct 16 15:17:38 azone-iMac.local racoon[359]: IPSec Phase1 started (Initiated by me).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Initiator, Main-Mode message 1).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: receive success. (Initiator, Main-Mode message 2).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Initiator, Main-Mode message 3).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: receive success. (Initiator, Main-Mode message 4).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Initiator, Main-Mode message 5).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKEv1 Phase1 AUTH: success. (Initiator, Main-Mode Message 6).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKE Packet: receive success. (Initiator, Main-Mode message 6).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IKEv1 Phase1 Initiator: success. (Initiator, Main-Mode).
Oct 16 15:17:38 azone-iMac.local racoon[359]: IPSec Phase1 established (Initiated by me).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IPSec Phase2 started (Initiated by me).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Initiator, Quick-Mode message 1).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IKE Packet: receive success. (Initiator, Quick-Mode message 2).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Initiator, Quick-Mode message 3).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IKEv1 Phase2 Initiator: success. (Initiator, Quick-Mode).
Oct 16 15:17:39 azone-iMac.local racoon[359]: IPSec Phase2 established (Initiated by me).
Oct 16 15:17:39 azone-iMac.local pppd[3799]: IPSec connection established
Oct 16 15:17:59 azone-iMac.local pppd[3799]: L2TP cannot connect to the server
Oct 16 15:17:59 azone-iMac.local racoon[359]: IPSec disconnecting from server [My Server IP Address]
Oct 16 15:17:59 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Information message).
Oct 16 15:17:59 azone-iMac.local racoon[359]: IKEv1 Information-Notice: transmit success. (Delete IPSEC-SA).
Oct 16 15:17:59 azone-iMac.local racoon[359]: IKE Packet: transmit success. (Information message).
Oct 16 15:17:59 azone-iMac.local racoon[359]: IKEv1 Information-Notice: transmit success. (Delete ISAKMP-SA).

Anyone help? Thanks a million!