If you want to access an iLO (Ilo2, Ilo3, Bladesystem) behind a firewall, there are some TCP ports that need to be opened on the firewall to allow all iLO traffic to flow through:

Secure Shell (SSH) :  TCP/22
Remote Console/Telnet:  TCP/23
Web Server Non-SSL :  TCP/80
Web Server SSL: TCP/443
Terminal Services: TCP/3389
Virtual Media:  TCP/17988
Shared Remote Console: TCP/9300
Console Replay:  TCP/17990
Raw Serial Data: TCP/3002
IPMI over LAN:  TCP/623