Linux知识点小结

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Linux知识点小结

#!/bin/bash

flagFile="/root/centos6-init.executed"

precheck(){

  if [[ "$(whoami)" !="root" ]]; then
  echo "please run this script as root ." >&2
  exit 1
  fi

  if [ -f "$flagFile" ]; then
  echo "this script had been executed, please do not execute again!!" >&2
  exit 1
  fi

  echo -e "\033[31m WARNING! THIS SCRIPT WILL \033[0m\n"
  echo -e "\033[31m *1 update the system; \033[0m\n"
  echo -e "\033[31m *2 setup security permissions; \033[0m\n"
  echo -e "\033[31m *3 stop irrelevant services; \033[0m\n"
  echo -e "\033[31m *4 reconfig kernel parameters; \033[0m\n"
  echo -e "\033[31m *5 setup timezone and sync time periodically; \033[0m\n"
  echo -e "\033[31m *6 setup tcp_wrapper and netfilter firewall; \033[0m\n"
  echo -e "\033[31m *7 setup vsftpd; \033[0m\n"
  sleep 5
  
}

yum_update(){
  yum -y update
  #update system at 5:40pm daily
  echo "40 3 * * * root yum -y update && yum clean packages" >> /etc/crontab
}

permission_config(){
  #chattr +i /etc/shadow
  #chattr +i /etc/passwd
}

selinux(){
  sed -i 's/SELINUX=disabled/SELINUX=enforcing/g' /etc/sysconfig/selinux
  setenforce 1
}

stop_services(){
  for server in `chkconfig --list |grep 3:on|awk '{print $1}'`
  do
    chkconfig --level 3 $server off
  done
   
  for server in crond network rsyslog sshd iptables
  do
    chkconfig --level 3 $server on
  done
}

limits_config(){
cat >> /etc/security/limits.conf <> /etc/rc.local
}

sysctl_config(){
sed -i 's/net.ipv4.tcp_syncookies.*$/net.ipv4.tcp_syncookies=1/g' /etc/sysctl.conf
sed -i 's/net.ipv4.ip_forward.*$/net.ipv4.ip_forward=1/g' /etc/sysctl.conf
cat >> /etc/sysctl.conf <> /root/.ssh/authorized_keys
  chmod 600 /root/.ssh/authorized_keys
  fi

  #sed -i '/^#Port/s/#Port 22/Port 65535/g' /etc/ssh/sshd_config
  sed -i '/^#UseDNS/s/#UseDNS no/UseDNS yes/g' /etc/ssh/sshd_config
  #sed -i 's/#PermitRootLogin yes/PermitRootLogin no/g' /etc/ssh/sshd_config
  sed -i 's/#PermitEmptyPasswords yes/PermitEmptyPasswords no/g' /etc/ssh/sshd_config
  sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/g' /etc/ssh/sshd_config
  /etc/init.d/sshd restart
}

time_config(){
  #timezone
  echo "TZ='Asia/Shanghai'; export TZ" >> /etc/profile

  # Update time
  if [! -f "/usr/sbin/ntpdate"]; then
    yum -y install ntpdate
  fi
  
  /usr/sbin/ntpdate pool.ntp.org
  echo "30 3 * * * root (/usr/sbin/ntpdate pool.ntp.org && /sbin/hwclock -w) &> /dev/null" >> /etc/crontab
  /sbin/service crond restart
}

iptables(){
cat > /etc/sysconfig/iptables << EOF
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:syn-flood - [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p icmp -m limit --limit 100/sec --limit-burst 100 -j ACCEPT
-A INPUT -p icmp -m limit --limit 1/s --limit-burst 10 -j ACCEPT
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j syn-flood
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A syn-flood -p tcp -m limit --limit 3/sec --limit-burst 6 -j RETURN
-A syn-flood -j REJECT --reject-with icmp-port-unreachable
COMMIT
EOF
/sbin/service iptables restart
source /etc/profile
}

other(){
  # initdefault
  sed -i 's/^id:.*$/id:3:initdefault:/' /etc/inittab
  /sbin/init q
  
  # PS1
  #echo 'PS1="\[\e[32m\][\[\e[35m\]\u\[\e[m\]@\[\e[36m\]\h \[\e[31m\]\w\[\e[32m\]]\[\e[36m\]$\[\e[m\]"' >> /etc/profile
   
  # Wrong password five times locked 180s
  sed -i '4a auth    required   pam_tally2.so deny=5 unlock_time=180' /etc/pam.d/system-auth
}

vsftpd_setup(){
  yum -y install vsftpd
  mv /etc/vsftpd/vsftpd.conf /etc/vsftpd/vsftpd.conf.bak
  touch /etc/vsftpd/chroot_list
  setsebool -P ftp_home_dir=1
cat >> /etc/vsftpd/vsftpd.conf <
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