All IPv4 addresses:
cat access.log |awk '/^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/ {print $1}'
All IPv6 addresses:
cat access.log |awk '!/^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/ {print $1}'
Unique first block prefixes:
cat access.log |awk '!/^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/ {print $1}'| awk -F: '{print $1}'|sort -n| uniq -c|sort -nr
Unique full prefixes (but might be full address):
cat access.log |awk '!/^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/ {print $1}'| awk -F:: '{print $1}'|sort|uniq -c|sort -nr