Sites pinging in the night

I ran a packet sniffer the last two nights after my computer was rebooted just before going to bed. There are 3 sites being pinged (I think that is what is happening with ICMP) during the night: colostate.edu (Co State), isi.edu (U of S. Ca), and 113.142.8.219 (CHINANET). Nothing is running on the computer on my part.

12974 2013-12-25 21:12:34.295787000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9064, seq=2707/37642, ttl=64 (request in 12970)
12975 2013-12-25 21:12:34.295829000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9064, seq=2707/37642, ttl=63
12976 2013-12-25 21:12:34.295844000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9064, seq=2707/37642, ttl=62
12977 2013-12-25 21:12:34.295859000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9064, seq=2707/37642, ttl=61
123494 2013-12-25 23:26:57.706433000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9167, seq=4600/63505, ttl=64 (request in 123491)
123495 2013-12-25 23:26:57.706460000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9167, seq=4600/63505, ttl=63
123496 2013-12-25 23:26:57.706473000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9167, seq=4600/63505, ttl=62
123497 2013-12-25 23:26:57.706490000 pinger6.netsec.colostate.edu ICMP Echo (ping) reply id=0x9167, seq=4600/63505, ttl=61

196516 2013-12-26 00:53:20.822190000 pinger-j2.ant.isi.edu ICMP Echo (ping) reply id=0xe454, seq=3319/63244, ttl=64 (request in 196513)
196517 2013-12-26 00:53:20.822218000 pinger-j2.ant.isi.edu ICMP Echo (ping) reply id=0xe454, seq=3319/63244, ttl=63
196518 2013-12-26 00:53:20.822232000 pinger-j2.ant.isi.edu ICMP Echo (ping) reply id=0xe454, seq=3319/63244, ttl=62
196519 2013-12-26 00:53:20.822247000 pinger-j2.ant.isi.edu ICMP Echo (ping) reply id=0xe454, seq=3319/63244, ttl=61
406345 2013-12-26 04:42:42.900216000 pinger-w3.ant.isi.edu ICMP Echo (ping) reply id=0xa275, seq=588/19458, ttl=64 (request in 406342)
406346 2013-12-26 04:42:42.900245000 pinger-w3.ant.isi.edu ICMP Echo (ping) reply id=0xa275, seq=588/19458, ttl=63
406347 2013-12-26 04:42:42.900259000 pinger-w3.ant.isi.edu ICMP Echo (ping) reply id=0xa275, seq=588/19458, ttl=62
406348 2013-12-26 04:42:42.900275000 pinger-w3.ant.isi.edu ICMP Echo (ping) reply id=0xa275, seq=588/19458, ttl=61

423034 2013-12-26 04:58:25.565534000 113.142.8.219 ICMP Echo (ping) reply id=0x3680, seq=0/0, ttl=64 (request in 423030)
423035 2013-12-26 04:58:25.565563000 113.142.8.219 ICMP Echo (ping) reply id=0x3680, seq=0/0, ttl=63
423036 2013-12-26 04:58:25.565577000 113.142.8.219 ICMP Echo (ping) reply id=0x3680, seq=0/0, ttl=62
423037 2013-12-26 04:58:25.565594000 113.142.8.219 ICMP Echo (ping) reply id=0x3680, seq=0/0, ttl=61

Does anyone know what might be doing this pinging? Co. State might be Windows7 setting the time automatically, but what the others are doing in there, I don’t know. I am also running Comodo firewall. Any suggerstions for a better forum to ask this in? Thanks.