I have established a l2tp connection in my Ubuntu 20.04 machine as a client to the remote server. After the establishment, the server assigned itself an IP address of 192.168.18.162 and assigned the client (Ubuntu 20.04) 192.168.18.1. And the subnetwork 192.168.18.xxx is a newly creately one by the l2tp (ppp) connection. When I run $ip a, it shows the following network interface:
5: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1410 qdisc fq_codel state UNKNOWN group default qlen 3 link/ppp inet 192.168.18.1 peer 192.168.18.162/32 scope global ppp0 valid_lft forever preferred_lft forever
Then I ran $sudo tcptrack -i ppp0, and next I tried to ping both from the server using $ping 192.168.18.1 and from the client using $ping 192.168.18.162, to my surprise, there were no activities shown in the tcptrack screen. It means such ping packets do not go through ppp0?
