How to bye pass Firewall
To bye pass the Firewall you must know the firewall identification means full information about Firewall like type , version , and rules of almost every firewall on a Network.
These are three technique for Firewall Identification
- Port scanning
- Firewalking
- Banner grabbing
Port Scanning (How to bye pass Firewall)
- Check Point\’s FireWall-1 listens on TCP ports 256, 257, 258, and 259
- Check Point NG listens on TCP ports 18210, 18211, 18186, 18190, 18191, and 18192 as well
- Microsoft\’s Proxy Server usually listens on TCP ports 1080 and 1745
Here we are providing you , the ways by which you can conceal your Scanning
- Randomize target ports
- Randomize target addresses
- Randomize source ports
- Distributed source scans
- Using multiple computers on the Internet, each taking a small portion of the scanning targets
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Block unneeded ICMP packets at your border router
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Use an Intrusion Detection System, such as Snort
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IPPL is a Linux daemon that detects port scans (link Ch 901)
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Cisco routers have ACL rules to block scans
Firewalking (How to bye pass Firewall)
Firewalking is a method to collect information from remote network that are behind firewalls. Firewalk Looks Through a Firewall
- First Firewalk sends out a series of packets towards the destination with TTL=1, 2, 3, …
- When the target (Router3) is reached, that determines the TTL for the next phase
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In this example, the Target is at TTL=3, so all future packets will use TTL=4
Phase 2: Firewalking
- TCP or UDP paclets are sent from the scanning host to the Destination
- They all have TTL=4
Firwalking Countermesure
- You can block \”ICMP TTL expired\” packets at the gateway
- But this may negatively affect its performance
- Because legitimate clients connecting will never know what happened to their connection
Banner Grabbing
Banner are messages sent out by network services while connecting to the service.They announce which service is running on System
Banner grabbing is simple method of OS detection, its also help to find services runs by Firewall. there are three measure services send out through it is TELNET , FTP and Web Server.
Banner Grabbing Countermeasures
- Eliminate the open port on your firewall
- If you must leave the ports open on the external interface of your firewall
How to bye pass Firewall
Breaching Firewall
Byepassing a firewall using HTTP Tunnel
Placing Backdoors through Firewall
Hiding behind a Covert channel : Loki
The above topic and tools to bye pass firewall cover in next post as How to bye pass Firewall 2
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