[strongSwan] Frequent rekey causes lost tunnel after about 30 minutes

[Ruel, Ryan]

I’ve been performing some rekey testing, and purposely configured low lifetimes to force rekey’s to happen frequently in order to test the system.

I’m seeing that any rekey values less than 10m or so winds up causing issues, such as tunnels completely down, or the outbound SA deleted on one side (but the inbound SA remains).

I’ve just ran a test with two back to back Linux machines running 5.2.2.  In this case, I’m running the tunnel as transport mode over a GRE tunnel, but the problem seems to happen without the GRE tunnel as well:

conn b2b
    left=198.168.73.101
    leftsubnet=198.168.73.101/32[gre]
    leftid=198.168.73.101
    right=198.168.73.102
    rightsubnet=198.168.73.102/32[gre]
    rightid=198.168.73.102
    ike=aes-128-sha1-modp2048
    esp=null-sha256-noesn!
    type=transport
    auto=add

conn b2b
    left=198.168.73.102
    leftsubnet=198.168.73.102/32[gre]
    leftid=198.168.73.102
    right=198.168.73.101
    rightsubnet=198.168.73.101/32[gre]
    rightid=198.168.73.101
    ike=aes-128-sha1-modp2048
    esp=null-sha256-noesn!
    type=transport
    auto=add

I brought up the tunnel and left it running.  When I came back about 30 minutes later, both machines show:

Every 2.0s: setkey -D                                                                           Mon May  4 23:44:54 2015

No SAD entries.

I noticed this in one of the logs:
May  4 23:25:54 a198-168-73-102 charon: 04[IKE] initiator did not reauthenticate as requested
May  4 23:25:54 a198-168-73-102 charon: 04[IKE] reauthenticating IKE_SA b2b[5] actively

And the other side seems to be scheduling a re-auth event earlier:
May  4 23:15:54 a198-168-73-101 charon: 10[IKE] scheduling reauthentication in 600s
May  4 23:15:54 a198-168-73-101 charon: 10[IKE] maximum IKE_SA lifetime 600s
May  4 23:15:54 a198-168-73-101 charon: 10[IKE] received AUTH_LIFETIME of 600s, reauthentication already scheduled in 600s

Any ideas?  Is the reauth to blame?

I know this lifetime is unusually short, but I’m concerned that the same type of rekey issue may happen if I let the system run for much longer periods of time.

Thanks!

/Ryan
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