Re: [FW-1] th_flags 18 message_info TCP packet out of state

["Donna O'Connell" <donna.m.oconnell@FW1-NOSPAMVERIZON.COM>]

I was on the checkpoint site looking for something else and found this..
Thought I would forward it.

Solution Title:
 What to do when receiving errors in Log Viewer: "th_flags ## message_info TCP packet out of state"
Solution ID:
 skI4308
Creation Date:
 08/16/2001
Last Modified Date:
 11/30/2001


Environment:  Check Point NG
FireWall-1 NG
VPN-1 NG
Rule 0
Non SYN packet
Connections table
Kernel
TCP
Logging



Symptoms: Error in Log Viewer: "th_flags ## message_info TCP packet out of state"
Drop logs on rule 0


Cause: This error means that VPN-1/FireWall-1 intercepted a non-Syn packet which does not have an entry in the FireWall's connections table.
FireWall-1 will therefore drop the packet.


This error is the equivalent to the VPN-1/FireWall-1 4.1 error message: "Unknown established TCP packet". In VPN-1/FireWall-1 NG the mechanism has
been improved and the log may show more drops on rule 0 than were seen in FireWall-1 4.1. The error can be the result of several possible causes:


1. Dropping packets belonging to expired connections. Increasing the timeout of the related service can improve the situation.
2. Dropping packets after policy unload and load. In this case connections established when there is no policy are out of state, and cannot be matched
 to packets of already established connections.
3. Situations involving asymmetric routing, where all the TCP handshake packets were missed.
4. Direction enforcement for unidirectional connections, where packet flow is in the opposite direction to the connection direction.
5. TCP handshake direction enforcement, where some of the TCP handshake packets are in the wrong direction.

Solution: To allow non-Syn packets which do not have state information in the connections table to be matched against the Rule Base:


On FireWall-1 NG FP1 and above
========================
Using dbedit, edit the following property to "1" in the objects_5_0.C:
:fw_allow_out_of_state_tcp (0)
Press here to learn how to use dbedit


On FireWall-1 NG HF2 (Hotfix-2)
========================


UNIX
--------
1. Stop the FireWall (fwstop)


2. Perform the following platform dependant command:


Solaris:


Add the following line to the /etc/system file
set fw:fw_allow_out_of_state_tcp = 1


Linux:


Add the following parameter to the $FWDIR/bin/fwstart script. The change should look like this:


BEFORE -


. . . . insmod $smp_prefix -f $fwmod kver=$kver . . . . .


AFTER -


. . . . insmod $smp_prefix -f $fwmod kver=$kver fw_allow_out_of_state_tcp = 1. . . .


3. Reboot the machine !


Windows NT / 2000
-----------------------------
1. Add the following DWORD to the registry under:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\FW1\Parameters

A variable named AllowOutOfStateTCP should be added with a value of 1.


2. Reboot !


NOTE: If one wishes to just prevent these logs from getting into the Log Viewer proceed as follows:


UNIX
--------
1. Stop the FireWall (fwstop)


2. Perform the following platform dependant command:


Solaris:


Add the following line to the /etc/system file
set fw:fw_log_out_of_state_tcp = 0


Linux:


Add the following parameter to the $FWDIR/bin/fwstart script. The change should look like this:


BEFORE -


. . . . insmod $smp_prefix -f $fwmod kver=$kver . . . . .


AFTER -


. . . . insmod $smp_prefix -f $fwmod kver=$kver fw_log_out_of_state_tcp = 0. . . .


3. Reboot the machine !


Windows NT / 2000
-----------------------------
1. Add the following DWORD to the registry under:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\FW1\Parameters

A variable named DisableLogOutOfStateTCP should be added with a value of 1.


2. Reboot the machine !

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