If you are talking about restricting "hacking" attempts across multiple services (like ssh, smtp and http) then you are beginning to move into the realm of an IDS solution (like Snort)
Currently I use denyhosts plus iptables blacklist for ssh on the servers side (plus multiple layers of firewall devices in front of the servers)... I could go with either denyhosts OR iptables, but I believe multiple methods is prudent in case one method fails
This is what my (editted) iptables listing looks like for the blacklisting
Chain INPUT (policy DROP) target prot opt source destination SSH tcp -- anywhere anywhere state NEW tcp dpt:ssh
Chain BLACKLIST (3 references) target prot opt source destination all -- anywhere anywhere recent: SET name: BLACKLIST side: source DROP all -- anywhere anywhere
Chain SSH (1 references) target prot opt source destination DROP all -- anywhere anywhere recent: UPDATE seconds: 3600 hit_count: 1 name: BLACKLIST side: source all -- anywhere anywhere recent: SET name: COUNT1 side: source all -- anywhere anywhere recent: SET name: COUNT2 side: source all -- anywhere anywhere recent: SET name: COUNT3 side: source BLACKLIST all -- anywhere anywhere recent: UPDATE seconds: 60 hit_count: 5 name: COUNT1 side: source BLACKLIST all -- anywhere anywhere recent: UPDATE seconds: 300 hit_count: 10 name: COUNT2 side: source BLACKLIST all -- anywhere anywhere recent: UPDATE seconds: 1800 hit_count: 20 name: COUNT3 side: source ACCEPT all -- anywhere anywhere
So if someone connects via ssh more than 5 times in one minute, 10 times in 5 minutes or 20 times in 30 minutes, they are blacklisted for an hour...
"Neil Aggarwal" neil@JAMMConsulting.com Sent by: centos-bounces@centos.org 07/09/2009 09:57 AM Please respond to CentOS mailing list centos@centos.org
To "'CentOS mailing list'" centos@centos.org cc
Subject [CentOS] Looking for recommendations for blocking hacking attempts
Hello:
I have been looking into projects that will automatically restrict hacking attempts on my servers running CentOS 5.
I think the two top contenders are: DenyHosts - http://denyhosts.sourceforge.net Fail2ban - http://www.fail2ban.org
From what I see, DenyHosts only blocks based on failed
SSH attempts whereas Fail2ban blocks failed attempts for other access as well.
The main benefit I see from DenyHosts is their synchronization service where my servers can proactively block hosts recognized by other users of their service.
Does anyone have experience with these tools and have recommendations?
Thanks, Neil
-- Neil Aggarwal, (281)846-8957, www.JAMMConsulting.com Will your e-commerce site go offline if you have a DB server failure, fiber cut, flood, fire, or other disaster? If so, ask me about our geographically redudant database system.
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