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 at JAMMConsulting.com>
Sent by: centos-bounces at centos.org
07/09/2009 09:57 AM
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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
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