[VPN] Re: Testing if IPSec is being blocked by ISP

[John Spanos]

Hi All,

A lot of people on this list have probably wanted to diagnose a similar
problem....

I need to perform some sort of test to see if a clients ISP is blocking
IPSec.  I tried to do a port scan of UDP 500 (ISAKMP) and see if the
endpoint is open on this port.  I tried but got a port not listening
response from my port scanner.  I then tried it from my machine to a IPSec
firewall that I administer and connect to all the time but got the same
message.  So I assume this is not a proper test.  My question is how do I
test to see if IPSec is being blocked?  Are there any tools out there help
with this?  I stuck with UDP 500 because I wouldn't know where to start to
try testing ESP or AH (IP Protocols).  Any feedback is much appreciated.

Cheers.

John Spanos.