Ipsec Troubleshooting Commands - D-Link NetDefend DFL-210 User Manual

9.7.3. IPsec Troubleshooting
Commands
If certificates have been used in a VPN solution then the following should be looked at as a source
of potential problems:
• Check that the correct certificates have been used for the right purposes.
• Check that the certificate .cer and .key files have the same filename. For example, my_cert.key
and my_cert.cer.
• Check that the certificates have not expired. Certificates have a specific lifetime and when this
expires they cannot be used and new certficates must be issued.
• Check that the NetDefendOS date and time is set correctly. If the system time and date is wrong
then certificates can appear as being expired when, in fact, they are not.
• Consider time-zone issues with newly generated certificates. The NetDefend Firewall's timezone
may not be the same as the CA server's timezone and the certificate may not yet be valid in the
local zone.
• Disable CRL (revocation list) checking to see if CA server access could be the problem. CA
Server issues are discussed further in Section 9.6, "CA Server Access".

9.7.3. IPsec Troubleshooting Commands

A number of commands can be used to diagnose IPsec tunnels:
The ipsecstat console command
ipsecstat can be used to show that IPsec tunnels have correctly established. A representative
example of output is:
gw-world:/> ipsecstat
--- IPsec SAs:
Displaying one line per SA-bundle
IPsec Tunnel
------------
L2TP_IPSec
IPsec_Tun1
To examine the first IKE negotiation phase of tunnel setup use:
gw-world:/> ipsecstat -ike
To get complete details of tunnel setup use:
gw-world:/> ipsecstat -u -v
The ikesnoop console command
A common problem with setting up IPsec is a list of proposed algorithms that is unacceptable to the
device at the other end of the tunnel. The ikesnoop command is a useful tool for diagnosing
incompatible algorithm proposal lists by showing the details of negotiations during tunnel setup.
The basic form of this command is:
gw-world:/> ikesnoop -on -verbose
Local Net
--------------
214.237.225.43
192.168.0.0/24
396
Remote Net
------------
84.13.193.179
172.16.1.0/24
Chapter 9. VPN
Remote GW
-------------
84.13.193.179
82.242.91.203