[프로토콜] l2tp(Linux xl2tpd)

참고:위키> https://namu.wiki/w/502%20Bad%20Gateway

Layer 2 Tunneling Protocol (L2TP) 

used to support virtual private networks (VPNs) 

or as part of the delivery of services by ISPs

does not provide any encryption or confidentiality by itself. 

it relies on an encryption protocol that it passes within the tunnel to provide privacy.

L2TP uses UDP port 1701 (<== Server Port ???) <== ALL CF> Below image. & linked packet.

LAC (L2TP Access Concentrator)

LNS (L2TP Network Server).

<WireShark Packet Samples>

nb6-http.pcap Three different HTTP requests: first was sent on the private IPv4 network (IPoE), second was sent on the public IPv4 network, third was sent on the public IPv6 network (L2TP tunnel).