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block the port using RHEL inbulit firewall

Posted on 2008-06-22
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Last Modified: 2008-07-30
Hi,
kindly let me know how to block the port using RHEL inbulit firewall

Thanks in advance
Naresh
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Question by:sitg
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6 Comments
 
LVL 19

Expert Comment

by:http:// thevpn.guru
ID: 21840491
iptables -A INPUT -p tcp --dport 21 -j DROP

Change the port number
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Expert Comment

by:Blaz
ID: 21843886
Or for the rule to work for sure use:
iptables -I INPUT -p tcp --dport 21 -j DROP

Rule order is important - the above rule inserts the rule to the start of firewall chain and drops the packet as soon as the firewall chain gets processed.
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LVL 19

Expert Comment

by:Gabriel Orozco
ID: 21931408
If the port is not trusted it should be in state disabled.<br><br>check here: <br><a rel="nofollow" href="http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/sysadmin-guide/s1-redhat-config-kickstart-firewall.html" target="_blank">http://www.redhat.com/docs<wbr>/manuals/e<wbr>nterprise/<wbr>RHEL-4-Man<wbr>ual/<wbr>sysadm<wbr>in-guide/s<wbr>1-redhat-c<wbr>onfig-kick<wbr>start-fire<wbr>wall.html</a><br><br>if it is enabled, just click in the checkbox.<br><br>the other way, much in the form previously described, is to insert the blocking rule as Blaz and shakoush2001 described, test it block the port you were looking for, and THEN sve the rules so the change is made permanent:<br><br>/sbin/service iptables save<br><br>that's it.<br>you can get much more information here:<br><a rel="nofollow" href="http://searchenterpriselinux.techtarget.com/tip/0,289483,sid39_gci1162861,00.html" target="_blank">http://searchenterpriselin<wbr>ux.techtar<wbr>get.com/ti<wbr>p/<wbr>0,289483<wbr>,sid39_gci<wbr>1162861,00<wbr>.html</a>
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LVL 19

Accepted Solution

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Gabriel Orozco earned 250 total points
ID: 22096801
er.. I object

my post was incorrectly pasted, but it say how to block the port *using the built in redhat firewall* as the user requested.

let me copy it by hand here:
If the port is not trusted it should be in state disabled.

check here: http://www.redhat.com/docs<wbr>/manuals/e<wbr>nterprise/

which is the RHEL-4-Man sysadmin-guide. it says:
if it is enabled, just click in the checkbox and save.

the other way, much in the form previously described, is to insert the blocking rule as Blaz and shakoush2001 described, test it block the port you were looking for, and THEN save the rules so the change is made permanent:

/sbin/service iptables save

that's it.

you can get much more information here:
http://searchenterpriselinux.techtarget.com/tip/0,289483,sid39_gci1162861,00.html

hope this time it got posted correctly.       
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