Some Linux Tips

• How to list all the open ports and programs:

  [linux]$ netstat -apne --inet
  [freebsd]$ sockstat

• How to list all the open files and programs:

  [linux]$ lsof
  [freebsd]$ fstat

• How to find information about an ip (i.e. 10.0.0.0):

  [unix]$ host 10.0.0.0
  [unix]$ dig -x 10.0.0.0

• How to find information about an ip owner (i.e. 10.0.0.0):

  [unix]$ whois -h whois.arin.net 10.0.0.0

• How to find out the mailserver for an ip:

  [unix]$ dig mx some.domain.name.net

• How to generate a filename with yesterdays date (i.e. for logfiles/backups):

  [linux]$ touch logfile-`date -dyesterday '+%Y-%m-%d'`
  [freebsd]$ touch logfile-`date -v-1d '+%Y-%m-%d'`