basic linux security tip

linux is open source operating system with unix like kernel. founder linux, linus trovald say if linux is for open source development. in linux system we know about firewall can use to protect our system from attack outside. phising, malware, spam or denial of service. below tips for basic security for protect your system :

1. open just for use port for your system you can use iptables for open and close port on your system.
2. change your password for one week
   
3. change default port for ssh with 2222 or other and filter your outside network for access it
   
4. use secure ftp for file transfer
   
5. limit udp trafic from outside network to protect your network or system from denial of service.
6. change permision file with read only
   
7. and last always update your repisitory
   

usually linux use iptables for default firewall. but we can use ip chains if that more familiar.