BruteForce Attacks

> first solution method: -Captcha-

	> secondn solution method: temporarily block or throttle the IP
	>Limit SSH Connections Per IP / Host :
	/sbin/iptables -A INPUT -p tcp –syn –dport 22 -m connlimit –connlimit-above 3 -j REJECT
	# save the changes see iptables-save man page, the following is redhat and friends specific command
	service iptables save
	>Limit HTTP Connections Per IP / Host :
	/sbin/iptables -A INPUT -p tcp –syn –dport 80 -m connlimit –connlimit-above 20 -j REJECT –reject-with tcp-reset
	# save the changes see iptables-save man page, the following is redhat and friends specific command
	service iptables save
	>Skip proxy server IP 1.2.3.4 from this kind of limitations:
	/sbin/iptables -A INPUT -p tcp –syn –dport 80 -d ! 1.2.3.4 -m connlimit –connlimit-above 20 -j REJECT –reject-with tcp-reset
	>Class C Limitations:
	/sbin/iptables -A INPUT -p tcp –syn –dport 80 -m connlimit –connlimit-above 20 –connlimit-mask 24 -j REJECT –reject-with tcp-reset
	# save the changes see iptables-save man page
	service iptables save
	>Limit Connections Per Second
	#!/bin/bash
	IPT=/sbin/iptables
	# Max connection in seconds
	SECONDS=100
	# Max connections per IP
	BLOCKCOUNT=10
	# default action can be DROP or REJECT
	DACTION=”DROP”
	$IPT -A INPUT -p tcp –dport 80 -i eth0 -m state –state NEW -m recent –set
	$IPT -A INPUT -p tcp –dport 80 -i eth0 -m state –state NEW -m recent –update –seconds ${SECONDS} –hitcount ${BLOCKCOUNT} -j ${DACTION}

	Note:
	add increasing delay after each failed login attempt (i.e 20 seconds after second try, 30 seconds after third try, etc)
	after 3 failed login attempts show captcha puzzle
	after 10 lofin attempts lock the user out
	after 2 hours unlock the user account and send mail for change user cred.

	for more:
	https://portswigger.net/blog/preventing-username-enumeration
	https://www.troyhunt.com/owasp-top-10-for-net-developers-part-3/
	https://www.cirt.net/passwords
	https://wiki.owasp.org/index.php/Testing_for_Brute_Force_(OWASP-AT-004)

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