Point-to-Point Protocol (PPP)

PPP is used to transfer IP and other packet based traffic through a serial line. It can also be encapsulated over Ethernet with PPP-over-Ethernet (PPPoE) and over ATM with PPP-over-ATM (PPPoA); these are used by many ISP's (Internet Service Providers) for broadband Internet access.

PPP may use CHAP for authentication purposes.

History

Today most ISP's offer PPP for serial (telephone) line internet access.

The former internet standards SLIP and its compressed cousin CSLIP were used before PPP, but are obsolete now.

Protocol dependencies

• PPP can run directly over a serial line (dial-up or directly-connected asynchronous lines and synchronous lines such as T1/E1 lines).

• ISDN: PPP can run over an ISDN B channel.

• Ethernet: PPP can use Ethernet and other protocols in the LanProtocolFamily with PPPoE.

• ATM: PPP can use ATM with PPPoA.

Example traffic

XXX - Add example traffic here (as plain text or Wireshark screenshot).

Example Flow

PPP: Point-to-Point Protocol tutorial rfc 1661, wireshak PPP analysis

Wireshark

The PPP dissector is fully functional.

(See CaptureSetup/PPP for information on capturing PPP control protocol traffic).

Preference Settings

(XXX add links to preference settings affecting how PPP is dissected).

Example capture files

• SampleCaptures/PPPHandshake.cap PPP Handshake using Microsoft Windows VPN

• SampleCaptures/PPP-config.cap LCP and IPCP configuration of a Direct Cable Connection (WinXP)

• SampleCaptures/ppp-dialup-munged.pppd Linux pppd async dialup connect/disconnect. Note that the login info in the pppd capture file has been munged slightly thus 'pppdump -p ...' shows that certain of the HDLC frames have a bad FCS).

Display Filter

A complete list of PPP display filter fields can be found in the display filter reference

Show only the PPP based traffic:

 ppp

Capture Filter

There's currently no support for filtering on any PPP fields other than the protocol.

External links

• RFC 1661 The Point-to-Point Protocol (PPP) (various other PPP related RFC's are available)

• Point-to-Point Protocol at Wikipedia.org

Discussion

Imported from https://wiki.wireshark.org/PPP on 2020-08-11 23:18:16 UTC