From the ChangeLog
What’s new in 6.22 (2014-Nov-11 14:46):
*) ovpn – added support for null crypto;
*) files – allow to remove empty disk folders;
*) sntp – fix problems with dns name resolving failures that were triggering
system watchdog timeout;
*) eoip/eoipv6/gre/gre6/ipip/ipipv6/6to4 tunnels have new features:
tunnels go down when no route to destination;
tunnels go down for 1 minute when transmit loop detected, warning gets logged;
new keepalive-retries setting;
keepalives enabled by default for new tunnels (10sec interval, 10 retries);
*) improved connection-state matcher in firewall – can match multiple states in one rule, supports negation;
*) added connection-nat-state matcher – can match connections that are srcnatted,dstnatted or both;
*) 100% CPU load caused by DNS service fixed;
*) 100% CPU load caused by unclassified services fixed;
*) 6to4 tunnel fixed;
*) new RouterBOOT firmware for Metal 2SHPn to improve wireless stability;
Download at http://www.mikrotik.com/download