VirtualBox里面的虚拟机和宿主机之间大量的报文是什么报文?

thelordsaves

在virtualBox中安装了ubuntu虚拟机，使用tcpdump -vv命令查看网卡上的报文，会不停打印大量的输出，类似下面：

1. 18:31:33.054087 IP (tos 0x0, ttl 64, id 27451, offset 0, flags [DF], proto TCP (6), length 40)
   
2.     192.168.0.104.56317 > alex-VirtualBox-2.local.ssh: Flags [.], cksum 0x82dd (correct), seq 8165, ack 11573412, win 4380, length 0
   
3. 18:31:33.103033 ARP, Ethernet (len 6), IPv4 (len 4), Reply 192.168.0.1 is-at c8:3a:35:2a:88:38 (oui Unknown), length 46
   
4. 18:31:33.375578 IP (tos 0x0, ttl 64, id 27452, offset 0, flags [DF], proto TCP (6), length 92)
   
5.     192.168.0.104.56317 > alex-VirtualBox-2.local.ssh: Flags [P.], cksum 0xf7b8 (correct), seq 8165:8217, ack 11573412, win 4380, length 52
   
6. 18:31:33.375780 IP (tos 0x0, ttl 64, id 30545, offset 0, flags [DF], proto TCP (6), length 108)
   
7.     alex-VirtualBox-2.local.ssh > 192.168.0.104.56317: Flags [P.], cksum 0x8281 (incorrect -> 0x745f), seq 11573412:11573480, ack 8217, win 141, length 68
   
8. 18:31:33.375866 IP (tos 0x0, ttl 64, id 30546, offset 0, flags [DF], proto TCP (6), length 924)
   
9.     alex-VirtualBox-2.local.ssh > 192.168.0.104.56317: Flags [P.], cksum 0x85b1 (incorrect -> 0xb067), seq 11573480:11574364, ack 8217, win 141, length 884
   
10. 18:31:33.376213 IP (tos 0x0, ttl 64, id 30547, offset 0, flags [DF], proto TCP (6), length 588)
    
11.     alex-VirtualBox-2.local.ssh > 192.168.0.104.56317: Flags [P.], cksum 0x8461 (incorrect -> 0x31ac), seq 11574364:11574912, ack 8217, win 141, length 548
    
12. 18:31:33.376327 IP (tos 0x0, ttl 64, id 30548, offset 0, flags [DF], proto TCP (6), length 332)
    
13.     alex-VirtualBox-2.local.ssh > 192.168.0.104.56317: Flags [P.], cksum 0x8361 (incorrect -> 0xab78), seq 11574912:11575204, ack 8217, win 141, length 292
    
14. 18:31:33.376422 IP (tos 0x0, ttl 64, id 30549, offset 0, flags [DF], proto TCP (6), length 332)
    
15.     alex-VirtualBox-2.local.ssh > 192.168.0.104.56317: Flags [P.], cksum 0x8361 (incorrect -> 0xa8e2), seq 11575204:11575496, ack 8217, win 141, length 292
    
16. 18:31:33.376469 IP (tos 0x0, ttl 64, id 27453, offset 0, flags [DF], proto TCP (6), length 92)
    
17.     192.168.0.104.56317 > alex-VirtualBox-2.local.ssh: Flags [P.], cksum 0x9fff (correct), seq 8217:8269, ack 11573412, win 4380, length 52
    
18. 18:31:33.376474 IP (tos 0x0, ttl 64, id 27454, offset 0, flags [DF], proto TCP (6), length 40)
    
19.     192.168.0.104.56317 > alex-VirtualBox-2.local.ssh: Flags [.], cksum 0x7fab (correct), seq 8269, ack 11574364, win 4142, length 0
    
20. 18:31:33.376475 IP (tos 0x0, ttl 64, id 27455, offset 0, flags [DF], proto TCP (6), length 92)
    
21.     192.168.0.104.56317 > alex-VirtualBox-2.local.ssh: Flags [P.], cksum 0x2294 (correct), seq 8269:8321, ack 11574364, win 4142, length 52
    

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其中alex-VirtualBox是本人的虚拟机，192.168.0.4是宿主机IP。
这些报文都是什么报文？有什么作用？