first try

etc-cron.daily-anonymize-pafal

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+# simple cronjob to anonymize IPv4 and IPv6 addresses
+#   in pafakedaccesslog logfile entries
+#   on a Debian GNU/Linux default Apache2 and PHP installation
+#   placed in /etc/cron.daily/ .
+
+# config
+readonly LOG="/var/www/html/pafal/faccess.log"
+
+# ipv4
+/bin/sed -i -E 's/^([[:digit:]]{1,3}\.)([[:digit:]]{1,3}\.)([^ ]*)(.*)/\1\20.0\4/' "${LOG}"
+
+# ipv6
+/bin/sed -i -E 's/^([[:xdigit:]]{1,4}:)([[:xdigit:]]{1,4}:)([[:xdigit:]]{1,4}:)([^ ]*)(.*)/\1\2\3:0\5/' "${LOG}"
+
+exit 0