Cisco Simple GRE Tunnels (With IPSEC)
KB ID 0000951 Problem I’ve spent years setting up VPN tunnels between firewalls. The only time I’ve ever dealt with GRE is for letting VPN client software though firewalls. GRE’s job is to ‘encapsulate’ other protocols and transport those protocols inside a virtual point to point link. Below is the topology, I’m going to use. The tunnel will run form Router R1 to Router R3, once complete I should be...
Cisco PIX 500 – IPSEC Site to Site VPNs (v6)
KB ID 0000611 Problem Note: This is for firewalls running an operating system BEFORE version 7, if you have an PIX running version 7 or above go here instead. I’ll run though he commands first and then the configuration from PDM at the end. Solution PIX 500: Configure a site to site VPN from command line 1. Connect to the PIX, go to “enable mode”, then to “Configure terminal mode” User Access...
VPN Problem Cisco PIX v6 to Cisco ASA 5500
KB ID 0000761 Problem I found this out purely by accident today, while replacing an old PIX 506E that had died with an ASA 5505. The client’s other site still had a PIX 506E (Running 6.3(5)). I was setting up the VPN, and noticed something that WOULD have been a problem if I had not spotted it. Solution Essentially the older PIX firewalls are set for 3DES encryption, MD5 Hashing and Diffie Hellman 2. After version 8.4 the ASA...
Cisco ASA Site to Site VPN’sSite to Site ISAKMP VPN (Main Mode)
KB ID 0000213 Problem As with most things, before you have a hope of fixing something, you will stand a better chance if you know how it works in the first place. Below is a quick run though of what’s happening with your site to site VPN’s and how they work. For the entire process we will have two Cisco ASA 5500 firewalls and a site to site VPN. Solution What’s an Initiator and a Responder? 1. Our Laptop 192.168.1.50...
Troubleshooting Phase 1 Cisco Site to Site (L2L) VPN Tunnels
KB ID 0000216 Problem Site to Site VPN’s either work faultlessly straight away, or involve head scratching and a call to Cisco TAC, or someone like me to come and take a look. If I’m honest, the simplest and best answer to the problem is “Remove the Tunnel from both ends and put it back again”. Just about every VPN tunnel I’ve put in that did not work, was a result of my fat fingers putting in the wrong...