Using the Microsoft VPN client through Cisco ASA/PIX

KB ID 0000009 Dtd 05/09/12

Problem

You cannot open a Microsoft client VPN tunnel with a cisco PIX or ASA in front of you on the network.

Solution

You need the following open (outbound)

  • TCP port 1723 (thats pptp)
  • Protocol 47 (GRE) - note thats a PROTOCOL and NOT a PORT

Allow PPTP Client through the ASA via Command Line

1. Connect to the ASA then add PPTP inspection to the default inspection map.

PetesASA>
PetesASA> en
Password: ********
PetesASA# conf t
PetesASA(config)# policy-map global_policy
PetesASA(config)# (config-pmap)# class inspection_default
PetesASA(config)# inspect pptp
PetesASA(config)# 

2. Then allow the GRE protocol and TCP Port 1723 outbound.

PetesASA(config)# access-list outbound extended permit gre any any
PetesASA(config)# access-list outbound extended permit tcp any any eq pptp
PetesASA(config)# access-group outbound in interface inside 

3. Save the changes.

PetesASA(config)# write mem
Building configuration...
Cryptochecksum: 5c8dfc45 ee6496db 8731d2d5 fa945425 

8695 bytes copied in 3.670 secs (2898 bytes/sec) [OK] PetesASA(config)#

Allow PPTP Client through the ASA via ASDM (GUI)

1. Connect to the ASDM GUI interface. Configuration > Firewall > Access Rules > Add > Inside Interface > Allow > Source = Any > Detination = Any > Service = GRE > OK > Apply.

ASDM - Firewall Rules

2. In the same window > Add another rule > This time seelct TCP > Then select 'More Options'.

ASDM - Firewall Rule Allow Port

3. Change the Source/Service to tcp/pptp > OK > Apply.

Allow PPTP through ASA

4. To add PPTP inspection >Service Policy Rules > Seelct > Inspection_Default > Edit > Rule Actions > Tick PPTP > OK.

ASDM Add PPTP Inspection

5. Finally to save your work > File > Save running configuration to flash

ASDM - Save Changes

 

Related Articles, References, Credits, or External Links

Original Article Written 18/09/08

Author: Migrated

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