리눅스 명령어 netstat -altunp

열려있는 포트를 알아 볼 때 사용 한다. 매우 유용하다^-^good~
netstat -altunp

옵션 : 아래의 옵션은 man netstat 를 통해서 발췌한 내용이다.
 --verbose , -v
       Tell the user what is going on by being verbose. Especially print  some
       useful information about unconfigured address families.

--numeric , -n
       Show  numerical addresses instead of trying to determine symbolic host,
       port or user names.

   --numeric-hosts
       shows numerical host addresses but does not affect  the  resolution  of
       port or user names.

   --numeric-ports
       shows numerical port numbers but does not affect the resolution of host
       or user names.

   --numeric-users
       shows numerical user IDs but does not affect the resolution of host  or
       port names.

   --protocol=family , -A
       Specifies  the  address families (perhaps better described as low level
       protocols) for which connections are to be shown.  family  is  a  comma
       (’,’)  separated  list of address family keywords like inet, unix, ipx,
       ax25, netrom, and ddp.  This has the same effect as using  the  --inet,
       --unix (-x), --ipx, --ax25, --netrom, and --ddp options.

       The address family inet includes raw, udp and tcp protocol sockets.

   -c, --continuous
       This  will cause netstat to print the selected information every second
       continuously.

   -e, --extend
       Display additional information.  Use  this  option  twice  for  maximum
       detail.

   -o, --timers
       Include information related to networking timers.

-p, --program
       Show the PID and name of the program to which each socket belongs.

 -l, --listening
       Show only listening sockets.  (These are omitted by default.)

 -a, --all
       Show  both  listening and non-listening sockets.  With the --interfaces
       option, show interfaces that are not marked

   -F
       Print routing information from the FIB.  (This is the default.)

   -C
       Print routing information from the route cache.

   -Z --context
       If SELinux enabled print SELinux context.

   -T --notrim
       Stop trimming long addresses.

   delay
       Netstat will cycle printing through  statistics  every  delay  seconds.
       UP.

 netstat {--statistics|-s} [--tcp|-t] [--udp|-u] [--raw|-w] [delay]