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Old 04-20-2007, 05:55 AM   #1
bong.mau
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Registered: Apr 2004
Posts: 391

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linux firewall


Hi

the question is :
what is the command to chechk open ports in my computers ?

then if there are no open tcp/udp ports does still i need a firewall activated ?

thanks in advance

Maurizio
 
Old 04-20-2007, 07:16 AM   #2
alienux
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Registered: Sep 2006
Location: Dayton, Ohio
Distribution: Slackware 12, Fedora Core, PCLinuxOS
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Use the "netstat" command. There are various arguments for it.

For example, to list all processes and process ID associated with ports without mapping port numbers to friendly names, showing tcp ports, use:

Code:
netstat -anp --tcp
You can check

Code:
netstat --help
for more options.
 
Old 04-20-2007, 11:08 AM   #3
bong.mau
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Registered: Apr 2004
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i isssued the command..

[bong@localhost ~]$ netstat -anp --tcp
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 1 0 xxx.xxx.xxx.xxx:32791 yyy.yyy.yy.yyy:8080 CLOSE_WAIT 4451/konquerorz9GTL

i issued the command when connected to internet...

i omitted local address and foreign address with a seried pf x and y for privacy reason.....

it appears local tcp port 32791 is connected to remote 8080
please if i'm worng ..explain me..
the state column report Close_wait

what does this means.......?
that the connection is established but the port is closed ?

to be more clear......this morning i buy a linuxmagazine where a tip informed me that the concept of a firewall MUST ported from winxp may be not the same in linux if there are not open ports.......infact the tip continue to inform me that ubuntu has not a preconfigured firewall...

my env: is mandriva 10.1 running with shorewall
so i opened this thread to help me verifying this...


please help me clarifying my doubts...
if i am in a such situation does still i need a firewall ?


thanks in advance

Maurizio
 
  


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