Cisco PIX TCP Connection Prevention Help with the static command

Posted on 2006-05-09
Medium Priority
Last Modified: 2013-11-16
    Ok i am trying to implament this on our firewall's  they are pix 515 e
 software versoion 6.3
Here is the link to the cisco site...

and it says to use the static command and set the  emb_limit to 1

 this is from Cisco's site

" For discarded TCP connections originating from lower security level interfaces to higher security level interfaces, TCP Intercept can be configured on STATIC commands by setting the emb_limit to 1. This results in the PIX proxying all connection attempts after the first connection. The PIX will create and send the TCP SYN,ACK from the destination to the original source. Since the original TCP SYN packet was spoofed, the source IP address will not be tracking the TCP connection and it will send a TCP RST to the PIX. The PIX will then close the connection originating from the TCP SYN packet with the incorrect checksum. TCP Intercept may impact firewall performance and should be tested before being enabled in a production environment. "

When i enter the command i get

  [no] static [(internal_if_name, external_if_name)]
         {<global_ip>|interface} <local_ip> [dns] [netmask <mask>]
         [<max_conns> [<emb_limit> [<norandomseq>]]]
 [no] static [(internal_if_name, external_if_name)] {tcp|udp}
         {<global_ip>|interface} <global_port>
         <local_ip> <local_port> [dns] [netmask <mask>]
         [<max_conns> [<emb_limit> [<norandomseq>]]]

invalid number of interfaces specified
invalid syntax

  Please some one give me the correct way to put this command in ....

  Thanks experts in advance.....

Question by:vtobusman

Accepted Solution

stressedout2004 earned 500 total points
ID: 16640674
If you have an existing static command, you need to first removed it because the PIX won't allow you to overwrite it.

static (inside,outside) netmask 0 0

To change the embryonic connection from unlimited to 1 of the following static statement, the following
commands needs to be run on  PIX under configuration mode.

no static (inside,outside) netmask 0 0
static (inside,outside) netmask 0 1


Author Comment

ID: 16641277
Thanks a bunch i know it was something simple

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