PIX 501: Inside/Outside IP Addressing


Just to warn you before reading this: I barely know enough about subnetting to get by so excuse any stupid questions please. Anyway, I am trying to set up two network segments separated by my PIX. When I try and change the inside IP of the PIX I get an error:

pixfirewall(config)# show ip
System IP Addresses:
        ip address outside
        ip address inside
Current IP Addresses:
        ip address outside
        ip address inside
pixfirewall(config)# ip address inside
Sorry, not allowed to enter IP address on same network as interface 0

With a subnet mask of isn't 172.20.4.X on a different subnet as 172.20.6.X? Why is there a conflict?

Thanks in advance.

Who is Participating?
Keith AlabasterConnect With a Mentor Enterprise ArchitectCommented:
You have used a mask which includes both the outside ip range and the suggested inside ip range of, you cannot do this. If you want to use these addresses then change the subnet mask to

the mask = all addresses from -
the mask = 172.4.0 -

alternatively you could use

the mask = -

Whichever you choose, make sure that ALL devices on the subnets are changed to reflect the same subnet masks.

Keith AlabasterEnterprise ArchitectCommented:
Thank you :)
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