Oh, after a while, there are some output inside the container:
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
09:53:15.576023 IP (tos 0x0, ttl 128, id 16734, offset 0, flags [none], proto UDP (17), length 328)
172.21.17.196.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from c8:d3:ff:40:c5:11, length 300, xid 0xe54bbbed, Flags [none] (0x0000)
Client-IP 172.21.17.196
Client-Ethernet-Address c8:d3:ff:40:c5:11
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Inform
Client-ID Option 61, length 7: ether c8:d3:ff:40:c5:11
Hostname Option 12, length 9: "yadfsejie"
Vendor-Class Option 60, length 8: "MSFT 5.0"
Parameter-Request Option 55, length 13:
Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
Static-Route, Classless-Static-Route, Classless-Static-Route-Microsoft, Vendor-Option
Option 252
09:53:47.371857 IP (tos 0x0, ttl 128, id 32662, offset 0, flags [none], proto UDP (17), length 328)
172.21.17.148.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from c8:d3:ff:40:cb:b9, length 300, xid 0xe81ca296, Flags [none] (0x0000)
Client-IP 172.21.17.148
Client-Ethernet-Address c8:d3:ff:40:cb:b9
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Inform
Client-ID Option 61, length 7: ether c8:d3:ff:40:cb:b9
Hostname Option 12, length 4: "wang"
Vendor-Class Option 60, length 8: "MSFT 5.0"
Parameter-Request Option 55, length 13:
Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
Static-Route, Classless-Static-Route, Classless-Static-Route-Microsoft, Vendor-Option
Option 252
09:55:07.606466 IP (tos 0x0, ttl 128, id 17135, offset 0, flags [none], proto UDP (17), length 328)
172.21.17.196.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from c8:d3:ff:40:c5:11, length 300, xid 0x462097a9, Flags [none] (0x0000)
Client-IP 172.21.17.196
Client-Ethernet-Address c8:d3:ff:40:c5:11
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Inform
Client-ID Option 61, length 7: ether c8:d3:ff:40:c5:11
Hostname Option 12, length 9: "fewfe"
Vendor-Class Option 60, length 8: "MSFT 5.0"
Parameter-Request Option 55, length 13:
Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
Static-Route, Classless-Static-Route, Classless-Static-Route-Microsoft, Vendor-Option
Option 252
09:55:32.210099 IP (tos 0x0, ttl 128, id 67, offset 0, flags [none], proto UDP (17), length 328)
172.21.17.148.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request from c8:d3:ff:40:cb:b9, length 300, xid 0x7a2f3198, Flags [none] (0x0000)
Client-IP 172.21.17.148
Client-Ethernet-Address c8:d3:ff:40:cb:b9
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: Inform
Client-ID Option 61, length 7: ether c8:d3:ff:40:cb:b9
Hostname Option 12, length 4: "wang"
Vendor-Class Option 60, length 8: "MSFT 5.0"
Parameter-Request Option 55, length 13:
Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
Static-Route, Classless-Static-Route, Classless-Static-Route-Microsoft, Vendor-Option
Option 252
But according to the MAC, it’s not related to the container.