sh is ugh

hex_to_ip ()
{
    test $# -ge 1 || return;
    local HEX B1 B2 B3 B4;
    HEX=`echo $1 | tr '[:lower:]' '[:upper:]'`;
    H1=`echo $HEX | cut -c1-2`
    H2=`echo $HEX | cut -c3-4`
    H3=`echo $HEX | cut -c5-6`
    H4=`echo $HEX | cut -c7-8`
    B1=`echo 10 o 16 i $H1 p | dc`
    B2=`echo 10 o 16 i $H2 p | dc`
    B3=`echo 10 o 16 i $H3 p | dc`
    B4=`echo 10 o 16 i $H4 p | dc`
    echo "$B1.$B2.$B3.$B4"
}