How activate TCP encapsulation on PIX 515 for Cisco VPN Clients?

Discussion in 'Cisco' started by Otmar Spoettel, Nov 24, 2005.

  1. Hello,

    how can i activate TCP encapsulation for Cisco VPN clients on the PIX
    515, instead of UDP NAT/PAT?

    I must use on the VPN-Client Side the option "Enable Transport
    tunneling" -> "IPsec over TCP", because i have some "lowcost" locations
    with "lowcost" router/firewalls.

    This router/firewalls have a buggy NAT/PAT implementation (PAT is not
    working for Ports lower 1024).

    So if more than 1 user tries to open a VPN-Client connection, the first
    user will be disconnected.

    I have found this in the FAQs:
    Q. I am experiencing problems with only one VPN Client (for releases 3.3
    and earlier) being able to connect through a Port Address Translation
    (PAT) device. What can I do to alleviate this problem?

    A. There was a bug in several Network Address Translation (NAT)/PAT
    implementations that causes ports less than 1024 not to be translated.
    On the VPN Client 3.1, even with NAT transparency enabled, the Internet
    Security Association and Key Management Protocol (ISAKMP) session uses
    UDP 512. The first VPN Client goes through the PAT device and keeps
    source port 512 on the outside. When the second VPN Client connects,
    port 512 is already in use. The attempt fails.

    There are three possible workarounds.

    Fix the PAT device.
    Upgrade the VPN Clients to 3.4 and use TCP encapsulation.
    Install a VPN 3002 that replaces all VPN Clients.

    My option is only solution 2 (Upgrade the VPN Clients to 3.4 and use TCP

    I have clients newer than 3.4 (4.0.4rel)
    Now how i must configure the PIX to work with TCP encapsulation?

    Thank you for your help!

    Otmar Spoettel, Nov 24, 2005
    1. Advertisements

  2. the TCP encap is for VON concentrators.
    get the client 3.6.x or a 4.xx and issue the PIX command isakmp nat-t

    This works just fine.

    Martin Bilgrav, Nov 25, 2005
    1. Advertisements

  3. and what is your PIX OS Version ?
    get 6.3.xx hopefully the latest 6.3.5 or minimum 6.3.3
    Martin Bilgrav, Nov 25, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.