I currently learn to configure my cisco pix 506e firewall. I am now precisely experimenting "fixup" statements and I just remarked that when I activate "fixup protocol dns maximum-length 512" I cannot make any telnet to any protocol on my cisco pix from wan side.
For example, without any "fixup protocol dns" I can well make "telnet 184.108.40.206 80" and type basic HTTP statements like "GET / HTTP/1.0" but if activate "fixup protocol dns" I cannot make anymore telnet to port 80, 25 ...
Can somebody explain me if this is a normal behaviour and why ?
Many thanks for your comprehension.
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