pcap_loop exited with value -2

[RonaldinhoL]

我的环境是VPN环境，内网把所有端口都封了，所以使用的 --raw-mode icmp 模式，但是连接一直无法建立。客户端 mac os 10.14.6, 服务端 centos 6.3。
客户端日志：

[2020-01-11 14:19:18][INFO]source_addr is now 172.22.19.165
[2020-01-11 14:19:18][INFO]using port 12918
[2020-01-11 14:19:18][INFO]filter expression is [ip and icmp and src 10.77.144.61]
[2020-01-11 14:19:18][DEBUG]pcap_loop exited with value -2
[2020-01-11 14:19:18][INFO]breakloop() succeed after 3 attempt(s)
[2020-01-11 14:19:18][INFO]state changed from client_idle to client_pre_handshake
[2020-01-11 14:19:18]INFOsent handshake1
[2020-01-11 14:19:19][INFO]changed state from to client_handshake1 to client_handshake2,my_id is 65daddb5,oppsite id is d6afea32
[2020-01-11 14:19:19]INFOsent handshake2
[2020-01-11 14:19:21]INFOsent handshake2
[2020-01-11 14:19:22]INFOsent handshake2
[2020-01-11 14:19:23]INFOsent handshake2
[2020-01-11 14:19:24]INFOsent handshake2
[2020-01-11 14:19:25][INFO]state back to client_idle from client_handshake2
[2020-01-11 14:19:25][DEBUG]created new udp_fd 10
[2020-01-11 14:19:25][INFO]source_addr is now 172.22.19.165
[2020-01-11 14:19:25][INFO]using port 41499
[2020-01-11 14:19:25][INFO]filter expression is [ip and icmp and src 10.77.144.61]
[2020-01-11 14:19:25][DEBUG]pcap_loop exited with value -2
[2020-01-11 14:19:25][INFO]breakloop() succeed after 9 attempt(s)
[2020-01-11 14:19:25][INFO]state changed from client_idle to client_pre_handshake
[2020-01-11 14:19:25]INFOsent handshake1
[2020-01-11 14:19:26][INFO]changed state from to client_handshake1 to client_handshake2,my_id is 35aedee1,oppsite id is 8ab6b809
[2020-01-11 14:19:26]INFOsent handshake2
[2020-01-11 14:19:28]INFOsent handshake2

服务端日志：

[2020-01-11 14:19:12][INFO][172.22.19.165:29389]got packet from a new ip
[2020-01-11 14:19:12][INFO][172.22.19.165:29389]created new conn,state: server_handshake1,my_id is 880bba0c
[2020-01-11 14:19:12][INFO][172.22.19.165:29389]changed state to server_handshake1,my_id is 880bba0c
[2020-01-11 14:19:13][INFO][172.22.19.165:29389]received handshake oppsite_id:2c6bf737 my_id:880bba0c
[2020-01-11 14:19:13][INFO][172.22.19.165:29389]oppsite const_id:89e0b9c8
[2020-01-11 14:19:13][INFO][172.22.19.165:29389]changed state to server_ready
[2020-01-11 14:19:18][INFO][172.22.19.165:12918]got packet from a new ip
[2020-01-11 14:19:18][INFO][172.22.19.165:12918]created new conn,state: server_handshake1,my_id is d6afea32
[2020-01-11 14:19:18][INFO][172.22.19.165:12918]changed state to server_handshake1,my_id is d6afea32
[2020-01-11 14:19:19][INFO][172.22.19.165:12918]received handshake oppsite_id:65daddb5 my_id:d6afea32
[2020-01-11 14:19:19][INFO][172.22.19.165:12918]oppsite const_id:89e0b9c8
[2020-01-11 14:19:19][INFO][172.22.19.165:12918]grabbed a connection
[2020-01-11 14:19:25][INFO][172.22.19.165:41499]got packet from a new ip
[2020-01-11 14:19:25][INFO][172.22.19.165:41499]created new conn,state: server_handshake1,my_id is 8ab6b809
[2020-01-11 14:19:25][INFO][172.22.19.165:41499]changed state to server_handshake1,my_id is 8ab6b809
[2020-01-11 14:19:26][INFO][172.22.19.165:41499]received handshake oppsite_id:35aedee1 my_id:8ab6b809
[2020-01-11 14:19:26][INFO][172.22.19.165:41499]oppsite const_id:89e0b9c8
[2020-01-11 14:19:26][INFO][172.22.19.165:41499]grabbed a connection
[2020-01-11 14:19:34][INFO][172.22.19.165:12918]inactive conn cleared
[2020-01-11 14:19:39][INFO][172.22.19.165:41499]inactive conn cleared
[2020-01-11 14:21:58][INFO][172.22.19.165:33006]inactive conn cleared

两端都一直在重复连接，两边的 mtu都设置成和vpn一样了，大佬看一下不知道是啥问题？