Added fail2ban, though not sure its configured correctly yet

docker/rootfs/fail2ban/action.d/sendmail-common.conf

@@ -0,0 +1,78 @@
+## Version 2022/08/06
+# Fail2Ban configuration file
+#
+# Common settings for sendmail actions
+#
+# Users can override the defaults in sendmail-common.local
+
+[INCLUDES]
+
+after = sendmail-common.local
+
+[Definition]
+
+# Option:  actionstart
+# Notes.:  command executed on demand at the first ban (or at the start of Fail2Ban if actionstart_on_demand is set to false).
+# Values:  CMD
+#
+actionstart = printf %%b "Subject: [Fail2Ban] <name>: started on <fq-hostname>
+              Date: `LC_ALL=C date +"%%a, %%d %%h %%Y %%T %%z"`
+              From: <sendername> <<sender>>
+              To: <dest>\n
+              Hi,\n
+              The jail <name> has been started successfully.\n
+              Regards,\n
+              Fail2Ban" | <mailcmd>
+
+# Option:  actionstop
+# Notes.:  command executed at the stop of jail (or at the end of Fail2Ban)
+# Values:  CMD
+#
+actionstop = printf %%b "Subject: [Fail2Ban] <name>: stopped on <fq-hostname>
+             Date: `LC_ALL=C date +"%%a, %%d %%h %%Y %%T %%z"`
+             From: <sendername> <<sender>>
+             To: <dest>\n
+             Hi,\n
+             The jail <name> has been stopped.\n
+             Regards,\n
+             Fail2Ban" | <mailcmd>
+
+# Option:  actioncheck
+# Notes.:  command executed once before each actionban command
+# Values:  CMD
+#
+actioncheck =
+
+# Option:  actionban
+# Notes.:  command executed when banning an IP. Take care that the
+#          command is executed with Fail2Ban user rights.
+# Tags:    See jail.conf(5) man page
+# Values:  CMD
+#
+actionban =
+
+# Option:  actionunban
+# Notes.:  command executed when unbanning an IP. Take care that the
+#          command is executed with Fail2Ban user rights.
+# Tags:    See jail.conf(5) man page
+# Values:  CMD
+#
+actionunban =
+
+[Init]
+
+# Your system mail command
+#
+mailcmd = /usr/sbin/sendmail -f "<sender>" "<dest>"
+
+# Recipient mail address
+#
+dest = root
+
+# Sender mail address
+#
+sender = fail2ban
+
+# Sender display name
+#
+sendername = Fail2Ban