add update.motd

update.motd/50-fail2ban

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+logfile='/var/log/fail2ban.log*'
+mapfile -t lines < <(grep -hioP '(\[[a-z-]+\]) ?(?:restore)? (ban|unban)' $logfile | sort | uniq -c)
+jails=($(printf -- '%s\n' "${lines[@]}" | grep -oP '\[\K[^\]]+' | sort | uniq))
+
+out=""
+for jail in ${jails[@]}; do
+    bans=$(printf -- '%s\n' "${lines[@]}" | grep -iP "[[:digit:]]+ \[$jail\] ban" | awk '{print $1}')
+    restores=$(printf -- '%s\n' "${lines[@]}" | grep -iP "[[:digit:]]+ \[$jail\] restore ban" | awk '{print $1}')
+    unbans=$(printf -- '%s\n' "${lines[@]}" | grep -iP "[[:digit:]]+ \[$jail\] unban" | awk '{print $1}')
+    bans=${bans:-0} # default value
+    restores=${restores:-0} # default value
+    unbans=${unbans:-0} # default value
+    bans=$(($bans+$restores))
+    diff=$(($bans-$unbans))
+    out+=$(printf "$jail, %+3s bans, %+3s unbans, %+3s active" $bans $unbans $diff)"\n"
+done
+
+printf "\nfail2ban status (monthly):\n"
+printf "$out" | column -ts $',' | sed -e 's/^/  /'