Recently I was troubleshooting a Cisco VPN client issue. Cisco VPN client version 4.0.5 is installed on a Windows XP SP2 client with most recent Windows Security updates. After I installed and configured the VPN client I experienced some problems with it. A GPO was configured to enable the Windows Firewall when not connected to Active Directory domain and block traffic.
VPN connection was set for TCP tunneling on port 10000. I changed tunneling to UPD but got same result as with TCP tunneling. I googled and found one KB article from Microsoft.
I reviewed Windows Firewall configuration and indeed it was enabled.
I stopped the windows firewall with “cmd /k sc stop sharedaccess” and than I tried to reconnect again. The connection worked I had connection to my office network. After reading the KB article and stopping the firewall I realized we forgot to add the Cisco VPN client exception in the Active Directory GPO.