CentOS 6.5 initialization optimization script

CentOS 6.5 initialization optimization script
#!/bin/bashecho"This is the system initialization script. Run it with caution! "input_fun(){OUTPUT_VAR=$1INPUT_VAR=""while[-z$INPUT_VAR];doread-p"$OUTPUT_VAR"INPUT_VARdoneecho$INPUT_VAR}input_again(){MYHOSTNAME=$(input_fun"pleaseinputthehostname:")DOMAINNAME=$(input_fun"pleaseinputthedomainname:")CARD_TYPE=$(input_fun"pleaseinputcardtype(eth0):")IPADDR=$(input_fun"pleaseinputipaddress(192.168.100.1):")NETMASK=$(input_fun"pleaseinputnetmask(255.255.255.0):")GATEWAY=$(input_fun"pleaseinputgateway(192.168.100.1):")MYDNS1=$(input_fun"pleaseinputDNS1(114.114.114.114):")MYDNS2=$(input_fun"pleaseinputDNS2(8.8.4.4):")}input_againMAC=$(ifconfig$CARD_TYPE|grep"HWaddr"|awk-F[""]+'{print$5}')#SETCOMPUTERNAMEcat>/etc/sysconfig/network<<ENDFNETWORK=yesHOSTNAME=$MYHOSTNAMEENDFcat>/etc/sysconfig/network-scripts/ifcfg-$CARD_TYPE<<ENDFDEVICE=$CARD_TYPEBOOTPROTO=staticHWADDR=$MACNM_CONTROLLED=yesONBOOT=yesTYPE=EthernetIPV6INIT=noIPADDR=$IPADDRNETMASK=$NETMASKGATEWAY=$GATEWAYENDF/etc/init.d/networkrestartcat>/etc/hosts<<ENDF127.0.0.1$MYHOSTNAME$MYHOSTNAME.$DOMAINNAMElocalhost$IPADDR$MYHOSTNAME$MYHOSTNAME.$DOMAINNAMElocalhostENDFcat>/etc/resolv.conf<<ENDFdomain$DOMAINNAMEsearch$DOMAINNAMEnameserver$MYDNS1nameserver$MYDNS2ENDF# Disable SEKINUXsed-i's/SELINUX=enforcing/SELINUX=disabled/g'/etc/sysconfig/selinuxsetenforce0# Modifying the number of opened filesecho"*softnofile66666">>/etc/security/limits.confecho"*hardnofile66666">>/etc/security/limits.conf# Optimizing Kernel Parameterscat>>/etc/sysctl.conf<<ENDFnet.ipv4.tcp_max_syn_backlog=65536net.core.netdev_max_backlog=32768net.core.somaxconn=32768net.core.wmem_default=8388608net.core.rmem_default=8388608net.core.rmem_max=16777216net.core.wmem_max=16777216net.ipv4.tcp_timestamps=0net.ipv4.tcp_synack_retries=2net.ipv4.tcp_syn_retries=2net.ipv4.tcp_tw_recycle=1#net.ipv4.tcp_tw_len=1net.ipv4.tcp_tw_reuse=1net.ipv4.tcp_mem=94500000915000000927000000net.ipv4.tcp_max_orphans=3276800net.ipv4.ip_local_port_range=102465535ENDFsysctl-p# Shut Down services not used by the Systemforserverin`chkconfig--list|grep3:on|awk'{print$1}'`dochkconfig--level3$serveroffdoneforserverincrondnetworkrsyslogsshddochkconfig--level3$serverondone# Adding users and sudo Elevation of Privilegeuser_add(){USERNAME=$(input_fun"pleaseinputnewusername:")useradd$USERNAMEpasswd$USERNAME}user_addchmod+w/etc/sudoersecho"$USERNAMEALL=(ALL)ALL">>/etc/sudoerschmod-w/etc/sudoers# Set Time and time zone Synchronizationyum-yinstallntpdate/usr/sbin/ntpdatetime.nist.govecho"*/5****root/usr/sbin/ntpdatetime.nist.gov1>/dev/null2>&1">>/var/spool/cron/root# Configure SSHDsed-i'/^#Port/s/#Port22/Port65535/g'/etc/ssh/sshd_configsed-i'/^#UseDNS/s/#UseDNSyes/UseDNSno/g'/etc/ssh/sshd_configsed-i's/#PermitRootLoginyes/PermitRootLoginno/g'/etc/ssh/sshd_configsed-i's/#PermitEmptyPasswordsno/PermitEmptyPasswordsno/g'/etc/ssh/sshd_configiptables-AINPUT-ptcp--dport65535-jACCEPT/etc/init.d/sshdrestart