Solved

How Stateful Inspection handles ICMP, UDP.ESP and GRE Packets.

Posted on 2011-03-11
4
2,658 Views
Last Modified: 2012-05-11
so far I understand only TCP connection state  will be seen in connection table, or  stateful table will have track of all UDP,ESP,ICMP and GRE packets. which one is true ?

One more thing just wanna a know, whats a commands to see the stateful connection table  in firewalls (Checkpoint/Cisco ASA/Fortigate/Juniper)
 
What is DEEP inspection ???

0
Comment
Question by:tyrosec
  • 2
  • 2
4 Comments
 
LVL 69

Expert Comment

by:Qlemo
ID: 35115702
That are a lot of questions, and they can't be answered that simple. But I'll try.

Deep Inspection (DI) analyzes the payload of packets in addition to the header. SPI (stateful package inspection), which is what is done without DI, applies only on headers. With DI you can filter e.g. http traffic, inspecting and optionally removing any JavaScript contents.
SPI only cares if ingress traffic has been asked for, by comparing protocol, ports and IP addresses with its session table.

Regarding "see the stateful connection table", the command is similar but different for each firewall. I can tell only for ScreenOS (Juniper SSG/Netscreen), but expect it to be the same on Cisco and JunOS (Juniper SRX & Co):  show session . There are more options to restrict the output, and you can apply additional filter commands, but that is getting quite complex and very decice specific.

Stateful inspection and UDP: Connectionless session info is kept in the same session table as for TCP traffic. A timeout value allows for closing the session if either the application layer protocol is unknown, not allowing for terminating "commands", or on communication errors.
If an application layer gateway can be applied (the firewall knows about the protocol, and can hence "see" when a session is "closed"), the session will get closed out ASAP. E.g. for ICMP Echo Request (ping), the session info can be removed as soon as the ICMP Echo Reply, Timeout, Not Reachable etc. messages are received.
0
 

Author Comment

by:tyrosec
ID: 35115967
Hi  Qlemo... Certainly  I understand that ..one question i wanna understand

... we  have option that cisco firewalls  can be configured in stateful failover  i.e., HA(Active/standby)... standby Firewalls suppose to handle all the seesion when  active member goes down. Say  I have configured  IPsec Remote access VPN on active firewall &  I have connected VPN RA through my laptop,  tunnel is formed between my laptop &  active firewall , when failover happpen the standby member will be active,  AND Tunnel (my laptop and Firewall) will be remain undistrubed or  it will disconnet and we have manually connect  the RA VPN.

0
 
LVL 69

Accepted Solution

by:
Qlemo earned 500 total points
ID: 35115975
"stateful failover" implies that the state is failed over, too. Active/standby need to exchange session info all the time (from the active member to the passive). There might be a small lag, because failover does not work immediately (it needs a small amount of time to recognize the failure), but that should not be more than a short "hick-up". No service should break, including VPN.
0
 

Author Comment

by:tyrosec
ID: 35137633
But suggest some Materials to know boardly "How Stateful session handles the TCP/UDP/GRE/ICMP Protocol"  
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
clean-up rule netscreen firewall 3 89
Firewall port opening 2 67
Setting up a VPN 60 142
Issue with seeing default gateway on ASA 5506 firewall 4 47
In this tutorial I will show you with short command examples how to obtain a packet footprint of all traffic flowing thru your Juniper device running ScreenOS. I do not know the exact firmware requirement, but I think the fprofile command is availab…
I found an issue or “bug” in the SonicOS platform (the firmware controlling SonicWALL security appliances) that has to do with renaming Default Service Objects, which then causes a portion of the system to become uncontrollable and unstable. BACK…
This Micro Tutorial demonstrates using Microsoft Excel pivot tables, how to reverse engineer competitors' marketing strategies through backlinks.
Established in 1997, Technology Architects has become one of the most reputable technology solutions companies in the country. TA have been providing businesses with cost effective state-of-the-art solutions and unparalleled service that is designed…

803 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question