X forwarding + pollapla ssh

[I.Ioannou]

Prospathw na kanw X forwarding mesw pollaplwn ssh (openssh)
kanaliwn. Diladi :

Firewall-1 --ssh -X -->Firewall2---ssh -X -->Firewall3

To X forwarding apo to 1 sto 2 douleuei
An trexw to idio gia na paw apo to 2 sto 3, kai para to oti
exw ta settings swsta, kai fiaxnetai h $DISPLAY, otan trexw xterm
sto 3 pernw ena "Can't open display" na to xeromai.
Exw dokimasei kai to -g kai to -A sto ssh, 
kai den einai thema xhost (to exw swsta auto)
Kamia idea ? 

TIA
roryt