PoiNtEr->: HACKER's Diary 3

                             Difference between a dream and an aim. A dream requires soundless sleep, whereas an aim requires sleepless efforts.

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Tuesday, December 20, 2011

HACKER's Diary 3


Protect Yourself From DDOS and Brute Force Attacks using IPTABLES in linux

The Linux firewall is called iptables. Iptables is very powerful and features include :
1:Filtering - (blocking unwanted traffic). You can filter incoming and outgoing traffic by user, group, time/date, or service (application).
2:NAT (Routing). If your computer has two or more network cards (or if you are using virtualization) you can use a spare computer as a router, one network card connected to the Internet and the other to your LAN with iptables monitoring and filtering traffic.
3:Logging (monitoring) network traffic.
4:Block brute force or DOS attacks.




Block Brute Force attempts (SSH or other connections)
1:iptables -A INPUT -p tcp -m tcp --dport 22 -m tcp -m state --state NEW -m recent --set --name SSH --rsource
2:iptables -A INPUT -p tcp -m tcp --dport 22 -m recent --update --seconds 600 --hitcount 8 --rttl 3:name SSH --rsource -j DROP
iptables -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT










 DOS ATTACKS:
In Dos attack generally Attacker tries to flood the victim with large number of packets using hping3.
The Internet Control Message Protocol (ICMP) has many messages that are identified by a "type" field. You need to use 0 and 8 ICMP code types.
1:Zero (0) is for echo-reply
2:Eight (8) is for echo-request.

iptables -A OUTPUT -p icmp --icmp-type echo-request -j DROP  
OR 
iptables -A OUTPUT -p icmp --icmp-type 8 -j DROP

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