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Fine tune a script to insert router

Posted on 2011-02-14
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Last Modified: 2012-08-14
In Reference to thread, Say thanks to the person who helped me !
http://www.experts-exchange.com/Programming/Languages/Scripting/Perl/Q_26821466.html#a34894213

I noticed that :

# NET 172.21.240.0/23
Dhcp Server 1.1.1.1 add scope 172.21.240.0 255.255.254.0 "172.21.240.0-Vlan-551" ""
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 6 STRING "128.163.97.5" "128.163.1.6"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 3 STRING "172.21.244.1"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 51 STRING "604800"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 44 STRING "128.163.111.170" "128.163.111.171"

Put an invalid router option  optionvalue 3 STRING "172.21.244.1"

My calculations shows the gateway/router should be 172.21.240.1

I would appreciate someones help please

while ( <> )
{
	if ( /\# NET ([0-9]+\.[0-9]+\.[0-9]+)\.([0-9]+)/ ) { $net = $1; $lastNum = $2+1;  }
	else
	{
		s/set optionvalue 3 STRING \"0.0.0.0\"/set optionvalue 3 STRING \"$net\.$lastNum\"/;
	}
	print $_;
}

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Question by:richsark
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7 Comments
 
LVL 16

Expert Comment

by:sjklein42
ID: 34894537
Strange!  Is this with a different dhcp.txt input file?  Please post the input so I can try running it here.
0
 
LVL 16

Expert Comment

by:sjklein42
ID: 34894572
When I create a small file with just this input:

# NET 172.21.240.0/23
Dhcp Server 1.1.1.1 add scope 172.21.240.0 255.255.254.0 "172.21.240.0-Vlan-551" ""
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 6 STRING "128.163.97.5" "128.163.1.6"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 3 STRING "0.0.0.0"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 51 STRING "604800"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 44 STRING "128.163.111.170" "128.163.111.171"

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it generates the correct 172.21.240.1 output.

Are you sure the optionvalue 3 line in the input file has 0.0.0.0, like this:

Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 3 STRING "0.0.0.0"

If it doesn't have 0.0.0.0, it won't match.
0
 
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Author Comment

by:richsark
ID: 34894583
Ahh, so.... the orginal file did not have 0.0.0.0, it had

# NET ---
# NET 172.21.240.0/23
Dhcp Server 1.1.1.1 add scope 172.21.240.0 255.255.254.0 "172.21.240.0-Vlan-551" ""
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 6 STRING "128.163.97.5" "128.163.1.6"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 3 STRING "172.21.244.1"
Dhcp Server 1.1.1.1 Scope 172.21.240.0 set optionvalue 51 STRING "604800"

So I guess, would it be hard to counter these types to insure in fact the router is set right??

Thanks
0
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LVL 16

Expert Comment

by:sjklein42
ID: 34894602
To replace all the optionvalue 3 strings regardless of their IPs in the input file, use this:

while ( <> )
{
	if ( /\# NET ([0-9]+\.[0-9]+\.[0-9]+)\.([0-9]+)/ ) { $net = $1; $lastNum = $2+1;  }
	else
	{
		s/set optionvalue 3 STRING \"[0-9\.]+\"/set optionvalue 3 STRING \"$net\.$lastNum\"/;
	}
	print $_;
} 

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Author Comment

by:richsark
ID: 34894619
Cool, So the above has the correct logic right? I am just worried it may set what it wants, but I believe it does check the network regardless right?
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Accepted Solution

by:
sjklein42 earned 500 total points
ID: 34894651
To summarize the latest version of the code:

It grabs each #NET address, keeps the first 3 numbers and numerically adds "1" to the fourth number.  This is the gateway IP.

This new version of the code looks for the line containing "set optionvalue 3 STRING", whether it already has a non-zero IP or not, and substitutes the new gateway IP it computed from the #NET line.

The only difference is that the previous version of the code required the input IP to be all zeroes.  The new version doesn't care.  Nothing else changed.
0
 
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Author Closing Comment

by:richsark
ID: 34894786
Thanks !!!

Good work
0

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