Problem with TCP connection on KVM virtualization

[maxxer]

Hi.
I've a server with Ubuntu 12.04 and KVM.
pfSense is a virtual machine, I'm using 2.1 beta to be able to have virtio support.

Almost everything works fine, except the physical host which cannot make use of TCP connections.
From the ubuntu I can ping www.google.it, but if I try telnet, mailing or anything else the connection cannot be established.
From any other IP in the LAN internet works fine.

I'm sure it's a pfSense problem because I have another firewall VM with ZeroShell and if I run that up http works fine.

What can I check?
thanks

[maxxer]

apparently there's something else, probably in the firewall.
I have an IPSEC lan2lan vpn to another office, traffic from the other end to pfsense work, while the other way around just for UDP/ICMP packets. http doesn't work either!