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Hardening CentOS




This is ONLY for CentOS.

Contents

  • What will this script do?
  • Downloading the Script
  • Modifying the Variables
  • Run the Script
  • What to do afterwards

What will this script do?

  • Install useful packages such as tcpdump, mtr, zsh, perl and logrotate
  • Setup automatic yum updates
  • Set password policies
    • Passwords will expire every 180 days
    • Passwords may only be changed once a day
  • Set OS policies
    • Set idle users to be disconnected after 15 minutes
  • Install (if it is not installed) and configure IPTables firewall
    • Open specified TCP/UDP ports
    • Set rules to block common attacksSet up Connection Tracking
      • Syn Floods
      • Fragmented Packets
      • Malformed XMAS Packets
      • Drop NULL packets
      • Limit pings to 3 per second and bursts of 25
      • Discourage Port Scanning
  • Install DDoS Deflate
  • Install CHKROOTKIT
    • Scheduled to check daily for issues and email your Admin Email
    • More information about CHKROOTKIT is available at http://www.chkrootkit.org/
  • Install rkhunter (Root Kit Hunter)
  • Install LSM (Linux Socket Monitor)
    • Runs in the background and watches for changes in sockets
  • Secure the SSH Daemon
    • Change the SSH port to a random number
    • Create an "admin" user
    • Make it so only the "admin" user can be logged into over SSH

Downloading the Script

cd /root
wget http://www.rackbank.com/mirror/centos.sh
chmod +x centos.sh

Modifying the Variables

vim centos.sh


You may customize TCPPORTS and UDPPORTS, however the defaults in there now should cover most common processes.

Run the Script

./centos.sh

What to do afterwards

After it completes, you will get a message like:


****************************************** YOUR SERVER IS NOW HARDENED ------------------------------------------ SSH User: admin SSH Pass: 254457cb9448226 SSH Port: 5575 Admin Email: admin@fake.rackbank.com ****************************************** You must now reconnect to this server using the information above. Changing the SSH port has caused this connection to freeze. BEFORE CLOSING THIS WINDOW please note your information above.
 


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