how to make linux centos 5 distribution secured

hi all,
my manager want me to secure linux centos5 distribution in development or hosting purpose
and I have no Idea in that can you please guide me in that matter
any tutorial, how to topic, check list is very appriciated

regards
hatem gamal
hatem_from_mesrAsked:
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fosiul01Connect With a Mentor Commented:
1. use iptables / firewall  [ block every incomming port, open one by one]
2, use syslog or syslog-ng to move log file from server to any secure place , so that you can check for any aututhorize activity
3. dont login in the server As root, put a hard password for root, login as normal user then use sudo
4. use some thirdparty software to prevent too much login attempt such , portsentry, fail2ban, those will save you if any person try too much  login attept

6, Check log regularly

these are the basic ....
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hatem_from_mesrAuthor Commented:
hi fosiul01,
>>>1. use iptables / firewall  [ block every incomming port, open one by one]
can you tell me more details I'm beginner in that
regards
hatem gamal
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fosiul01Commented:
Ok
in Centos , we get firewall which i iptables

such as block everything


iptables -P INPUT DROP

iptables -A INPUT  -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
so it will block every input
now you will have to open suppose ssh, 80, 53
just open one by one

but there are other things to consider  about IPtables
such as blockign spoofing, Brutal attack .

just read on net about iptables

another product you can use Snort, to protect your server from hacker..


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hatem_from_mesrAuthor Commented:
hi fosiul01,
>>>now you will have to open suppose ssh, 80, 53
can you please provide me syntax
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fosiul01Commented:
iptables -A INPUT  -p tcp --dport 80 -j ACCEPT

so it will allow http connection to your web server

iptables -A INPUT  -p udp --dport 53 -j ACCEPT
iptables -A INPUT  -p tcp --dport 53 -j ACCEPT

this will allow dns request to your server


one more : if you dont want any service in web server , dont install  
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