Netstat without netstat

# Get all open ports in hex format
declare -a open_ports=($(cat /proc/net/tcp /proc/net/raw /proc/net/udp | grep -v "local_address" | awk '{ print $2 }'))

# Define function for converting
dec2ip () {
    ip=$1
    s=""
    for i in {1..4}; do 
    s='.'$((ip%256))$s && ((ip>>=8)); 
    done; 
    echo ${s:1} | sed 's/\./\n/g' | tac | sed ':a; $!{N;ba};s/\n/./g'
}

# Show all open ports and decode hex to dec
for tuple in ${open_ports[*]}; do 
    port=${tuple#*:}
    ip=${tuple%:*}
    echo $(dec2ip $((0x${ip}))):$((0x${port})); 
done | sort | uniq -c