[strongSwan] Packets not being encapsulated

Russ Cox russ.cox at e-dba.com
Wed Mar 23 16:36:32 CET 2011


Hi All,

I'm having a bit of a strange issue with a net-net vpn setup where packets
bound for the remote subnet don't appear to be getting encapsulated on
either gateway, I see no ESP packets other than those attributed with
existing functional tunnels.

I've tried tcpdumping on both endpoints, and can see icmp packets coming in
to the local gateway from hosts on both networks, but no ESP packets - and
none of it seems to get across the tunnel.

Any help would be greatly appreciated - I've tried doing the same thing with
IKEV2 (with a couple of required changes) and had exactly the same result.

Give me a shout if I can provide any additional information.

Thanks!

Russ

---------------------

Here's my setup

Rodney:
Debian lenny x86_64
Strongswan 4.2.4-5 - from repo
A number of existing working ikev1 tunnels set up to other networks/hosts

Granville:
Debian Squeeze x86_64
Strongswan 4.4.1-5.1 - from repo

Iptables on both hosts:
udp 500 and 4500 + esp open


192.168.0.0/24-----RODNEY----BRIGHTON_PUB_IP.........ESSEX_PUB_IP---NAT_ROUTER----GRANVILLE----192.168.6.0/24

Essex router nats absolutely everything to Granville (it's on the netgear
router's dmz)
--------------------------------------
ESSEX - IPSEC.CONF

config setup
         plutodebug=control
        nat_traversal=yes
        charonstart=no
        plutostart=yes

conn essex_brighton
        left=%defaultroute
        leftid=ESSEX_PUB_IP
        leftsubnet=192.168.6.0/24
        leftfirewall=yes
        right=BRIGHTON_PUB_IP
        rightsubnet=192.168.0.0/24
        forceencaps=yes
        keyexchange=ikev1
        authby=secret
        auto=add
--------------------------------------

BRIGHTON-IPSEC.CONF

config setup
         plutodebug=control
         nat_traversal=yes
        charonstart=yes
        plutostart=yes

conn essex_brighton
        left=BRIGHTON_PUB_IP
        leftsubnet=192.168.0.0/24
        leftfirewall=yes
        right=ESSEX_PUB_IP
        rightsubnet=192.168.6.0/24
        forceencaps=yes
        keyexchange=ikev1
        authby=secret
        auto=add

-----------------------------------

root at granville:~# ipsec status
000 "essex_brighton":
192.168.6.0/24===192.168.16.2:4500[ESSEX_PUB_IP]---192.168.16.1...BRIGHTON_PUB_IP:4500[BRIGHTON_PUB_IP]===192.168.0.0/24;
erouted; eroute owner: #2
000 "essex_brighton":   newest ISAKMP SA: #1; newest IPsec SA: #2;
000
000 #2: "essex_brighton" STATE_QUICK_I2 (sent QI2, IPsec SA established);
EVENT_SA_REPLACE in 4s; newest IPSEC; eroute owner
000 #2: "essex_brighton" esp.9c28ba55 at BRIGHTON_PUB_IP (0 bytes)
esp.c32b10a1 at 192.168.16.2 (0 bytes); tunnel
000 #1: "essex_brighton" STATE_MAIN_I4 (ISAKMP SA established);
EVENT_SA_REPLACE in 6962s; newest ISAKMP
000


rodney:~# ipsec status
000 "essex_brighton":
192.168.0.0/24===BRIGHTON_PUB_IP:4500...ESSEX_PUB_IP:4500===192.168.6.0/24;
erouted; eroute owner: #3909
000 "essex_brighton":   newest ISAKMP SA: #3898; newest IPsec SA: #3909;
000
000 #3909: "essex_brighton" STATE_QUICK_R2 (IPsec SA established);
EVENT_SA_REPLACE in 3285s; newest IPSEC; eroute owner
000 #3909: "essex_brighton" esp.360fcd9e at ESSEX_PUB_IP (0 bytes)
esp.295edd15 at BRIGHTON_PUB_IP (0 bytes); tunnel
000 #3899: "essex_brighton" STATE_QUICK_R2 (IPsec SA established);
EVENT_SA_REPLACE in 446s
000 #3899: "essex_brighton" esp.c32b10a1 at ESSEX_PUB_IP (0 bytes)
esp.9c28ba55 at BRIGHTON_PUB_IP (0 bytes); tunnel
000 #3898: "essex_brighton" STATE_MAIN_R3 (sent MR3, ISAKMP SA established);
EVENT_SA_REPLACE in 7635s; newest ISAKMP
000
Security Associations:
  none

------------------------

root at granville:~# ip xfrm state
src 192.168.16.2 dst BRIGHTON_PUB_IP
    proto esp spi 0x295edd15 reqid 16385 mode tunnel
    replay-window 32 flag af-unspec
    auth hmac(sha1) 0x0ba38e23a79f79f7f96690d2d166b315f60b60bb
    enc cbc(aes) 0xdf238a47bb128a41d94f60452411cd26
    encap type espinudp sport 4500 dport 4500 addr 0.0.0.0
src BRIGHTON_PUB_IP dst 192.168.16.2
    proto esp spi 0x360fcd9e reqid 16385 mode tunnel
    replay-window 32 flag af-unspec
    auth hmac(sha1) 0x015ec50f83fc414a681902bd935cf8560da4cbb2
    enc cbc(aes) 0x7e40d181e5c8ca5bfc35ed44b59c968d
    encap type espinudp sport 4500 dport 4500 addr 0.0.0.0
src 192.168.16.2 dst BRIGHTON_PUB_IP
    proto esp spi 0x9c28ba55 reqid 16385 mode tunnel
    replay-window 32 flag af-unspec
    auth hmac(sha1) 0x2345729df63869ea9a6df60f50508cf746860b02
    enc cbc(aes) 0xf90f83024f337ff85a8fc72392eaea8f
    encap type espinudp sport 4500 dport 4500 addr 0.0.0.0
src BRIGHTON_PUB_IP dst 192.168.16.2
    proto esp spi 0xc32b10a1 reqid 16385 mode tunnel
    replay-window 32 flag af-unspec
    auth hmac(sha1) 0x7f16f51d63369bec30ac74e4eef27d9a8ff81958
    enc cbc(aes) 0x047271d81f3a0483c34c0790fcc098c8
    encap type espinudp sport 4500 dport 4500 addr 0.0.0.0
root at granville:~# ip xfrm policy
src 192.168.6.0/24 dst 192.168.0.0/24
    dir out priority 2344 ptype main
    tmpl src 192.168.16.2 dst BRIGHTON_PUB_IP
        proto esp reqid 16385 mode tunnel
src 192.168.0.0/24 dst 192.168.6.0/24
    dir fwd priority 2344 ptype main
    tmpl src BRIGHTON_PUB_IP dst 192.168.16.2
        proto esp reqid 16385 mode tunnel
src 192.168.0.0/24 dst 192.168.6.0/24
    dir in priority 2344 ptype main
    tmpl src BRIGHTON_PUB_IP dst 192.168.16.2
        proto esp reqid 16385 mode tunnel
src ::/0 dst ::/0
    dir 4 priority 0 ptype main
src ::/0 dst ::/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 4 priority 0 ptype main
src 0.0.0.0/0 dst 0.0.0.0/0
    dir 3 priority 0 ptype main
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