On ClusterA and B I have installed the "openswan" package on Debian Squeeze.

ClusterA ip is 172.16.0.107, B is 172.16.0.108

When they ping one another, it does not reach the destination.

/etc/ipsec.conf:

version 2.0     # conforms to second version of ipsec.conf specification

config setup
        protostack=netkey
        oe=off

conn L2TP-PSK-CLUSTER
        type=transport
        left=172.16.0.107
        right=172.16.0.108
        auto=start
        ike=aes128-sha1-modp2048
        authby=secret
        compress=yes

/etc/ipsec.secrets:

172.16.0.107 172.16.0.108 : PSK "L2TPKEY"
172.16.0.108 172.16.0.107 : PSK "L2TPKEY"

Here is the result of ipsec verify on both machines:

root@cluster2:~# ipsec verify
Checking your system to see if IPsec got installed and started correctly:
Version check and ipsec on-path                                 [OK]
Linux Openswan U2.6.28/K2.6.32-5-amd64 (netkey)
Checking for IPsec support in kernel                            [OK]
NETKEY detected, testing for disabled ICMP send_redirects       [OK]
NETKEY detected, testing for disabled ICMP accept_redirects     [OK]
Checking that pluto is running                                  [OK]
Pluto listening for IKE on udp 500                              [OK]
Pluto listening for NAT-T on udp 4500                           [FAILED]
Checking for 'ip' command                                       [OK]
Checking for 'iptables' command                                 [OK]
Opportunistic Encryption Support                                [DISABLED]
root@cluster2:~#

This is the end of the output of ipsec auto --status:

000 "cluster": 172.16.0.108<172.16.0.108>[+S=C]...172.16.0.107<172.16.0.107>[+S=C]; prospective erouted; eroute owner: #0
000 "cluster":     myip=unset; hisip=unset;
000 "cluster":   ike_life: 3600s; ipsec_life: 28800s; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 0
000 "cluster":   policy: PSK+ENCRYPT+COMPRESS+PFS+UP+IKEv2ALLOW+lKOD+rKOD; prio: 32,32; interface: eth0;
000 "cluster":   newest ISAKMP SA: #1; newest IPsec SA: #0;
000 "cluster":   IKE algorithm newest: AES_CBC_128-SHA1-MODP2048
000
000 #3: "cluster":500 STATE_QUICK_R0 (expecting QI1); EVENT_CRYPTO_FAILED in 298s; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate
000 #2: "cluster":500 STATE_QUICK_I1 (sent QI1, expecting QR1); EVENT_RETRANSMIT in 13s; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate
000 #1: "cluster":500 STATE_MAIN_I4 (ISAKMP SA established); EVENT_SA_REPLACE in 2991s; newest ISAKMP; lastdpd=-1s(seq in:0 out:0); idle; import:admin initiate

000

Interestingly enough, if I do ike-scan on the server here's what happens:

Doesn't seem to take my ike settings into account

root@cluster1:~# ike-scan -M 172.16.0.108
Starting ike-scan 1.9 with 1 hosts (http://www.nta-monitor.com/tools/ike-scan/)
172.16.0.108    Main Mode Handshake returned
    HDR=(CKY-R=641bffa66ba717b6)
    SA=(Enc=3DES Hash=SHA1 Auth=PSK Group=2:modp1024 LifeType=Seconds LifeDuration(4)=0x00007080)
    VID=4f45517b4f7f6e657a7b4351
    VID=afcad71368a1f1c96b8696fc77570100 (Dead Peer Detection v1.0)

Ending ike-scan 1.9: 1 hosts scanned in 0.008 seconds (118.19 hosts/sec).  1 returned handshake; 0 returned notify
root@cluster1:~#

I can't tell what's going on here, this is pretty much the simplest config I can have according to the examples.