Download the new RouterOS 6.3 release over the torrent network: http://www.mikrotik.com/download/routeros-ALL-6.3.torrent
Otherwise please visit http://www.mikrotik.com/download to pick exact version!

6.3 changelog:

*) ssh - fixed denial of service;
*) traceroute - show mpls labels as well;
*) bug fix - sometimes some new interfaces could not be created properly any more (f.e. some pppoe clients could not connect);
*) console - added '/console clear-history' command that clears command-line history for all users, requires 'policy' policy;
*) sstp - limit packet queue for each device;
*) RB2011L - fixed occasional gigabit switch-chip lockup;
*) user manager - will warn on 1MB and stop before reaching minimum of 500KB disk space;
*) hotspot - do not account traffic to local hotspot pages;
*) ppp, hotspot - added ability to specify where to insert rate limiting queue, it's parent and type;
*) pptp, l2tp, sstp - allow to specify server via dns name;
*) dhcp - added ability to specify where to insert rate limiting queue;
*) www proxy - support ipv6 parent proxy;
*) webfig - fixed problem when opening quickset page country was automaticly changed to etsi;
*) traceroute - added mtr like pinging;
*) fix queues - correct queue was not installed when last child removed;
*) fix simple queues - sometimes some simple queues would stop working after configuration changes;
*) console - fixed issue with local variables having non-empty value before first assignment;
*) console - fixed command ":global name" without second argument to not create or change global variable "name", only effect is to make "name" refer to global variable.
*) console - fixed passing local variables as argument to function;
*) RB1200 - fixed crash when receiving over l2mtu size packets on some ethernet interfaces;