dhcp のパケットを見たい。
sudo tcpdump -i macvlan0 port 67 or port 68 -e -n
ただ、これだと凄く使いにくい。もっとわかりやすく見たい。
dhcpdump が便利。
tcpdump を使わずに dhcpdumpを使うともっと簡単にdhcpのパケットを追いかけることが出来る。専用コマンド便利ですね。
sudo apt install dhcpdump
利用例
sudo dhcpdump -i macvlan0
TIME: 2023-01-18 17:36:40.745
IP: 0.0.0.0 (52:54:0:60:2b:ac) > 255.255.255.255 (ff:ff:ff:ff:ff:ff)
OP: 1 (BOOTPREQUEST)
HTYPE: 1 (Ethernet)
HLEN: 6
HOPS: 0
XID: 5d5415d9
SECS: 1
FLAGS: 0
CIADDR: 0.0.0.0
YIADDR: 0.0.0.0
SIADDR: 0.0.0.0
GIADDR: 0.0.0.0
CHADDR: 52:54:00:60:2b:ac:00:00:00:00:00:00:00:00:00:00
SNAME: .
FNAME: .
OPTION: 53 ( 1) DHCP message type 1 (DHCPDISCOVER)
OPTION: 61 ( 19) Client-identifier ff:56:50:4d:98:00:02:00:00:ab:11:e7:5f:9b:8b:d2:86:d0:a4
OPTION: 55 ( 11) Parameter Request List 1 (Subnet mask)
3 (Routers)
12 (Host name)
15 (Domainname)
6 (DNS server)
26 (Interface MTU)
33 (Static route)
121 (Classless Static Route)
119 (Domain Search)
42 (NTP servers)
120 (SIP Servers DHCP Option)
OPTION: 57 ( 2) Maximum DHCP message size 576
OPTION: 12 ( 6) Host name ubuntu
---------------------------------------------------------------------------
TIME: 2023-01-18 17:36:43.761
IP: 0.0.0.0 (52:54:0:60:2b:ac) > 255.255.255.255 (ff:ff:ff:ff:ff:ff)
OP: 1 (BOOTPREQUEST)
HTYPE: 1 (Ethernet)
HLEN: 6
HOPS: 0
XID: 5d5415d9
SECS: 3
FLAGS: 0
CIADDR: 0.0.0.0
YIADDR: 0.0.0.0
SIADDR: 0.0.0.0
GIADDR: 0.0.0.0
CHADDR: 52:54:00:60:2b:ac:00:00:00:00:00:00:00:00:00:00
SNAME: .
FNAME: .
OPTION: 53 ( 1) DHCP message type 3 (DHCPREQUEST)
OPTION: 61 ( 19) Client-identifier ff:56:50:4d:98:00:02:00:00:ab:11:e7:5f:9b:8b:d2:86:d0:a4
OPTION: 55 ( 11) Parameter Request List 1 (Subnet mask)
3 (Routers)
12 (Host name)
15 (Domainname)
6 (DNS server)
26 (Interface MTU)
33 (Static route)
121 (Classless Static Route)
119 (Domain Search)
42 (NTP servers)
120 (SIP Servers DHCP Option)
OPTION: 57 ( 2) Maximum DHCP message size 576
OPTION: 54 ( 4) Server identifier 192.168.1.1
OPTION: 50 ( 4) Request IP address 192.168.1.193
OPTION: 12 ( 6) Host name ubuntu
---------------------------------------------------------------------------
参考資料
https://matoken.org/blog/2019/04/10/a-memo-to-capture-dhcp-packets/
