Cisco 2821 GRE Problems

[mebernstein]

I currently have a remote XP client trying to access our new vpn network from a remote location. The XP client is behind an at&t u-verse router. The flow diagram is below. I currently get a message on the XP client that GRE is not enabled or something of the sort, and it gets stuck on username and password verifying.

Flow Chart:

XP computer (192.168.1.100)

|

AT&t u-verse router (public ip)

|

Internet

|

Linksys RV082(192.168.0.1, public ip) configured with VPN passthrough enabled and portfowarded to allow pptp

|

Cisco 2821(192.168.0.100, 192.168.4.1) port fowared to allow pptp

|

Windows XP VPN server(192.168.4.91)

Yes i do know that the 2821 can do vpn however I was asked to do it this way.

How would i configure the 2821 (firewall is enabled) and what eles may need to be changed.

[Giuseppe Larosa]

Hello Michael,

GRE is another tunneling protocol an alternative to PPTP.

In your flow diagram you say you would like to setup a PPTP tunnel.

There can be combinations of the two protocols.

However, the following document can help

http://www.cisco.com/en/US/tech/tk827/tk369/technologies_configuration_example09186a00800949c0.shtml

GRE is a protocol over IP (protocol 47)

an acl that permits GRE is written as:

access-list 111 permit gre host x.x.x.x host y.y.y.y

Hope to help

Giuseppe