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>The ip_local_port_range parameters</TITLE
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>Securing and Optimizing Linux: RedHat Edition -A Hands on Guide</TH
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>6.7. The ip_local_port_range parameters</A
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>&#13; The <TT
CLASS="filename"
>/proc/sys/net/ipv4/ip_local_port_range</TT
> defines the local port range that is used by <SPAN
CLASS="acronym"
>TCP</SPAN
> and <SPAN
CLASS="acronym"
>UDP</SPAN
> traffic to choose the local
port. You will see in the parameters of this file two numbers: The first number is the first local port allowed for <SPAN
CLASS="acronym"
>TCP</SPAN
> and <SPAN
CLASS="acronym"
>UDP</SPAN
> traffic on the server, the
second is the last local port number. For high-usage systems you may change its default parameters to 32768-61000 -first-last.
</P
><P
>&#13; The default setup for the ip_local_port_range parameters under Red Hat Linux is:
<TT
CLASS="computeroutput"
>"1024 4999"</TT
>
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To change the values of ip_local_port_range, type the following command on your terminal:
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>&#13; [root@deep] /# <B
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>echo</B
> "32768 61000" &#62;/proc/sys/net/ipv4/ip_local_port_range
</PRE
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>
Add the above commands to the <TT
CLASS="filename"
>/etc/rc.d/rc.local</TT
> script file and you'll not have to type it again the next time you reboot your system.
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>
Edit the <TT
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>/etc/sysctl.conf</TT
> file and add the following line:
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>&#13; # Allowed local port range
net.ipv4.ip_local_port_range = 32768 61000
</PRE
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>
You must restart your network for the change to take effect. The command to manually restart the network is the following:
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>&#13; [root@deep] /# /etc/rc.d/init.d/network <B
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>restart</B
>
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>
<P
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><TT
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>&#13; Setting network parameters [ OK ]
Bringing up interface lo [ OK ]
Bringing up interface eth0 [ OK ]
Bringing up interface eth1 [ OK ]
</TT
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