I am playing around with raw sockets and manufactured packets in pure-perl (no Net::Pcap etc). Along the way I figured I needed to know the whether the machine was big-endian (network order) or little-endian.

Actually, I don't need to know this, but here is the code for detecting endianness for normal big and little 32bit machines. Extensions for 64bit welcome; but this works for me on Linux-IA32 and Solaris2.6-UltraSparc . 

@b = unpack('CCCC', pack('I', 0x04030201));

if    ($b[0] == 4 and
       $b[1] == 3 and
       $b[2] == 2 and
       $b[3] == 1 )
  { print "big-endian\n"; }
elsif ($b[0] == 1 and
       $b[1] == 2 and
       $b[2] == 3 and
       $b[3] == 4 )
  { print "little-endian\n"; }
else
  { print "funky-endian\n"; }

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In reply to Detecting machine Endian-ness by LunaticLeo

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