PT40314151: Enable iptables Logging

- new firewall settings added: log drop packets, number of similar packets to be logged per unit of time
- configured rsyslog to write packets matching firewall-drop in /var/log/sipxpbx/firewall/firewall-drop.log
- added new iptables chain LOGDROP
- added log rotate for firewall logs
PT40314151: Enable iptables Logging

- added new section Security in Firewall > Settings tab - trusted IPs entry, block DoS attempts (known attackers as friendly-scanner, sipvicious, Sundayddr, iWar, SipScan, Sipsak) and text area to add custom UAs to deny packets from. Added option to log such attemtps in firewall-sipdos.log file
- added option to log incoming SIP messages in firewall-sip.log file