How to manually delete an entry from the Connections Table

[Kaspars_Zibarts]

Not that you really need to use this often but it has saved my day once or twice a year. Great SK103876 is available but in a stressful situation calculating HEX numbers is the last thing you want to do and then compiling a complex command out of it is even more challenging 

This one-liner actually gives you an opportunity to generate all fw tab kill commands in one file for a pair of given IP addresses. Tested on R80.10 GW but I'm fairly confident it would work in R77. 

IPA="x.x.x.x"; IPB="y.y.y.y"; IPAHEX=`printf '%02x' ${IPA//./ }`; IPBHEX=`printf '%02x' ${IPB//./ }`; grep "$IPAHEX" table | grep "$IPBHEX" | grep "^<0000000" | awk  '{print $1" "$2" "$3" "$4" "$5" "$6}'|sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall

You will need to dump all your current connections into a file called table first of course. You may add this to front of the above to make it true one-liner.. But I found it easier to do this in two steps as you have more control

fw tab -t connections -u > table

And result is in file called listofall. Then you just execute those commands by copy-paste for example or chmod the file itself and run it.

Here's an example 

And of course, you can add port numbers if needed

[PhoneBoy]

Bravo!

[EdesLC]

Nice.

[Simon_Garay]

Thank you very much for sharing this information. 

[MKIT_NMG]

Modified it a bit, it's still ugly but we don't have to do anything now, apart from providing the values for IPA & IPB

#!/bin/bash

#Dump latest copy of connection table
fw tab -t connections -u > table

#Read input for IPA & IPB values
read -p "IPA: " IPAI
read -p "IPB: " IPBI

#The Decimal to Hex conversion takes place and generates the command file
IPA=${IPAI}; IPB=${IPBI}; IPAHEX=`printf '%02x' ${IPA//./ }`; IPBHEX=`printf '%02x' ${IPB//./ }`; grep "$IPAHEX" table | grep "$IPBHEX" | grep "^<0000000" | awk  '{print $1" "$2" "$3" "$4" "$5" "$6}'|sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall

#Execute commands generated in the file
/bin/bash listofall

[cosmos]

Going through my bit buckets of useful Check Point stuff, here's a version I wrote that validates the input and asks before deleting.

#!/bin/bash
#
# Check Point Firewall Connection Killer
#
# Version 0.02
#
# Changelog
#   v0.01
#       First release
#   v0.02
#       Added valid_ip
# 
#
# Based on the post at https://community.checkpoint.com/t5/Enterprise-Appliances-and-Gaia/How-to-manually-delete-an-entry-from-the-Connections-Table/td-p/13122
#
# It's crude and uses temporary files instead of stored arrays, could do with a fair bit of improvement BUT IT WORKS.
#
# Limited to IP's for now... conn table format at https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk65133
# for whoever wants to nail it down to ports.
#
# Credits:  Kaspars_Zibarts https://community.checkpoint.com/t5/user/viewprofilepage/user-id/11456
#           MKIT_NMG https://community.checkpoint.com/t5/user/viewprofilepage/user-id/4907
#           Mitch Frazier for valid_ip https://www.linuxjournal.com/content/validating-ip-address-bash-script

echo "Check Point Firewall Connection Killer" 

# fns
display_usage() { 
    echo -e "\nPlease ensure you are in the correct VS"
	echo -e "\nUsage:\ncpfck IP1 IP2\n" 
	} 

valid_ip()
{
    local  ip=$1
    local  stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?
    fi
    return $stat
}

# usage
if [  $# -le 1 ] 
then 
    display_usage
    exit 1
fi 

if [[ ( $# == "--help") ||  $# == "-h" ]] 
then 
    display_usage
    exit 0
fi 

#Read input for IPA & IPB values and test
IPA=$1
IPB=$2

#IP Test
for IP in "$@"
do
    if ! valid_ip $IP
    then
        echo -e "\nBad IP: $IP! Please correct and try again."
        display_usage
        exit 1
    fi
done

#The Decimal to Hex conversion
IPAHEX=$(printf '%02x' ${IPA//./ })
IPBHEX=$(printf '%02x' ${IPB//./ })

echo Checking connection table for VS $vsname...
echo
# dump connection table, do stuff
fw tab -t connections -u | grep "$IPAHEX" | grep "$IPBHEX" | grep "^<0000000" | awk  '{print $1" "$2" "$3" "$4" "$5" "$6}'|sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall

#Execute commands generated in the file
echo -e "\nThe following connections were found in the connection table:"
echo
cat listofall
echo "do you wish to delete them?"
select yn in "Yes" "No"; do
    case $yn in
        Yes ) echo ; echo "deleting connections..."; /bin/bash listofall; echo "the specified connections were deleted"; break;;
        No ) echo "no connections were deleted"; exit;;
    esac
done

[cosmos]

Aaaand for those out there still upgrading your SMS/MDS from R77.30 who have just implemented the new DHCP services, this one's for you,

#!/bin/bash
#
# Check Point Firewall DHCP Connection Killer
#
# Version 0.01
#
# Tired of your DHCP traffic dropped by fw_conn_post_inspect Reason: Handler 'dhcp_request_code' drop?
#
# This script does one thing: queries the connection table for DHCP _requests_ (dest port:67 protocol: UDP) and kills them, if you allow it
#
# Developed for using the new dhcp_request and dhcp_reply services in a policy - see sk104114
# https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk104114

CPPROFILE_PATH=tmp/.CPprofile.sh
    . $CPDIR/$CPPROFILE_PATH;

echo "Check Point Firewall DHCP Connection Killer" 
echo
echo Checking connection table for DHCP traffic on VS ${vsname}...

# dump connection table, do stuff
fw tab -t connections -u | grep "00000043, 00000011" | grep "^<0000000" | awk  '{print $1" "$2" "$3" "$4" "$5" "$6}'|sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall
# do same for dhcp replies, if necessary
# fw tab -t connections -u | grep "00000044, 00000011" | grep "^<0000000" | awk  '{print $1" "$2" "$3" "$4" "$5" "$6}'|sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' >> listofall

#Execute commands generated in the file
echo -e "\nThe following DHCP connections were found in the connection table:"
echo
cat listofall
echo "do you wish to delete them?"
select yn in "Yes" "No"; do
    case $yn in
        Yes ) echo ; echo "deleting connections..."; /bin/bash listofall; echo "the specified connections were deleted"; break;;
        No ) echo "no connections were deleted"; exit;;
    esac
done
rm listofall

[Kaspars_Zibarts]

wow! its still alive after 5 years! haha

[taladrovs]

Hi,

Great post!

I tried to use this on R80.20 version but it didn´t work. Can anyone knows if I have to change something in the script?

 Thanks a lot.

[Duc_Nguyen_Anh]

Greate !!

Many thank,

[Brandon_Cotter]

This really really saved the day for me today after SIP issues following a policy install (sk140112 "Traffic is dropped with error: "fw_handle_old_conn_recovery Reason: old packet rulebase drop"" for the Googlers). Thank you so much!

[Lukas_Sosnovec]

Hi Brandon,

I am facing the same problem, after policy install SIP VoIP streams is dropped on old packer rulebase drop, although the newly installed policy allows it. Deleting the connections from the fw table resolves the issue, so does rebooting the VoIP gateways. It seems that the old SIP sessions which can be active for a long time are somehow disrupted after policy install so the firewall 'forgets' corresponding UDP ports for VoIP data stream and I have to force the SIP session to be initiated again.

This happens only sometimes, I didn't figure the conditions yet.

Did you make any progress with this issue?

[Kaspars_Zibarts]

Hi Lukas - it's not really relevant to the topic here 🙂 best would we to start a new thread.

But my two cents: check the settings on connectivity persistence 

[Lukas_Sosnovec]

Hi Kaspar, I tried it already and it seem to help. But from the security view this can be considered just as a w/a...

Thanks for your point, i will no longer spam here and create a new thread.

[_Daniel_]

A wonderful post which saved us after changing a NAT rule to not to NAT but kept natting based on existing connections.

It was perfectly tested on R80.30

THANK you

[Andrew_Rawlinso]

Hi @Kaspars_Zibarts how would you go about using this including port numbers? We have a need to reset some connections coming in from particular source ports but leaving the other connections in place.

[Kaspars_Zibarts]

You can try this, seems to do the trick, I have highlighted the changed sections

IPA="x.x.x.x"; IPB="y.y.y.y"; SPORT="zzz"; DPORT="zzz"; SPORTHEX=`printf '%08x' ${SPORT}`; DPORTHEX=`printf '%08x' ${DPORT}`; IPAHEX=`printf '%02x' ${IPA//./ }`; IPBHEX=`printf '%02x' ${IPB//./ }`; grep "$IPAHEX" table | grep "$IPBHEX" | grep "$SPORTHEX" | grep "$DPORTHEX" | grep "^<0000000" | awk '{print $1" "$2" "$3" "$4" "$5" "$6}' |sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall

[Andrew_Rawlinso]

Thank you for your quick response - we will give this a try. Really appreciate the help.

[akhhc]

Here's how to clear sessions on Check Point Maestro. I was only concerned with traffic between IPA and IPB, no matter what port is was on, so I removed that part of your script.

# let's work in the temp directory
cd /var/log/tmp
# collect the tables from all SGMs in Maestro cluster, save to a file called 'table'
g_fw tab -t connections -u > table
# filter for IP addresses we wish to clear, format the command, save to a file called 'listofall'
IPA="10.1.1.1"; IPB="10.2.2.2"; IPAHEX=`printf '%02x' ${IPA//./ }`; IPBHEX=`printf '%02x' ${IPB//./ }`; grep "$IPAHEX" table | grep "$IPBHEX" | grep "^<0000000" | awk '{print $1" "$2" "$3" "$4" "$5" "$6}' |sed 's/ //g'|sed 's/</fw tab -t connections -x -e /g'|sed 's/>//g'|sed 's/;//g' > listofall
# copy command file to all SGMs
asg_cp2blades /var/log/tmp/listofall
# run script on all SGMs
g_all bash /var/log/tmp/listofall
# you will get errors for 'not found in table connections' these can be ignored.

[yura_k]

Colleagues, please help me to adapt this wonderful one-liner to solve the task of removing all UDP connections from the connection table.

I'm currently using fw ctl conntab -proto=17 -x , but perhaps there are more elegant options. We found that if ISP Redundancy is enabled, TCP sessions are reset when the ISP fails, but UDP sessions continue to be translated according to the old NAT rules until they are manually removed from the connection table or by timeout.