Ctrl-C works for me.
Cisco Fire Linux OS v6.0.0 (build 258)
Cisco Firepower Management Center for VMWare v6.0.0 (build 1005)
admin@sfvdc:~$
admin@sfvdc:~$ sudo ping
Password:
Usage: ping [-LRUbdfnqrvVaAD] [-c count] [-i interval] [-w deadline]
[-p pattern] [-s packetsize] [-t ttl] [-I interface]
[-M pmtudisc-hint] [-m mark] [-S sndbuf]
[-T tstamp-options] [-Q tos] [hop1 ...] destination
admin@sfvdc:~$ sudo ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_req=1 ttl=45 time=15.0 ms
64 bytes from 8.8.8.8: icmp_req=2 ttl=45 time=14.9 ms
64 bytes from 8.8.8.8: icmp_req=3 ttl=45 time=15.0 ms
64 bytes from 8.8.8.8: icmp_req=4 ttl=45 time=14.9 ms
64 bytes from 8.8.8.8: icmp_req=5 ttl=45 time=14.9 ms
64 bytes from 8.8.8.8: icmp_req=6 ttl=45 time=14.9 ms
^C
--- 8.8.8.8 ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5005ms
rtt min/avg/max/mdev = 14.900/14.991/15.056/0.165 ms
admin@sfvdc:~$