export of programs via ssh

Hello, I have the following situation: My workstation is Fedora 23, with the latest updates. I have also several virtual machines with Fedora23 and Centos 5/6/7. When I log in Fedora via ssh and try to run firefox from Fedora, there is no activity, it just stays and no export is coming on my screen. When I log in this machine via Windows (putty + xming), the export is fine. I have no problems with the export of lets say wireshark/xclock. The machine is with the latest firefox/kernel When I start firefox with strace, it says: --- SIGVTALRM {si_signo=SIGVTALRM, si_code=SI_TKILL, si_pid=5575, si_uid=1003} --- rt_sigreturn({mask=[]}) = -1 EINTR (Interrupted system call) wait4(5592, 0x7ffeecd03cc4, 0, NULL) = ? ERESTARTSYS (To be restarted if SA_RESTART is set) Similar problem is for Centos7 - firefox starts, but it's like hung - no url back, just gray window. Xclock export is fine. Windows putty session with firefox is fine Can someone give a hint what I am doing wrong? Regards,