the pack and unpack functions handle such data representation. $unsigned_local_long = pack("L",unpack("N",$unsigned_network_long)) will take the 4 (supposedly) bytes in $unsigned_network_long, interpret them into a perl scalar integer value. After the network format was unpacked, it is passed to pack, which then converts the perl scalar to a local C compiler representation of the integer, in 32 bits. You can see the documentation for a more complete reference of packing templates, but the ones you're probably interested in are:

N - network order long integer (unsigned)
n - network order short integer (unsigned)
V - a vax order ('host order') long integer (unsigned)
v - a vax order short (unsigned)
s - a local (network or vax, depending on processor) signed short (16 bits)
S - a local order unsigned short (16 bits)
l - a local order signed long (32 bits)
L - a local order unsigned long (32 bits)
i - a local order signed long (32/64 bits)
I - a local order unsigned long (32/64 bits)

If you suffix s/S/l/L with !, then they become the native width of 'shorts' and 'longs', as treated by the compiler which made perl. If you have a 64 bit processor, than the native integer width may be larger. A more comprehensive documentation of the templates and how to use them can be found in perlfunc -f pack.

-nuffin
zz zZ Z Z #!perl