What is the header length of AH and ESP?

Header length: the length of the header in 4 byte words . Header length = 5 if options are not used.

English for specific purposes (ESP) is a subset of English as a second or foreign language . It usually refers to teaching the English language to university students or people already in employment, with reference to the particular vocabulary and skills they need.

ESP tunnel mode encrypts the entire packet, including the original packet headers . ESP transport mode only encrypts the data, not the original headers; this is commonly used when the sending and receiving system can “speak” IPsec natively.

AH-style authentication authenticates the entire IP packet, including the outer IP header, while the ESP authentication mechanism authenticates only the IP datagram portion of the IP packet . Either protocol can be used alone to protect an IP packet, or both protocols can be applied together to the same IP packet.

Techopedia Explains Encapsulating Security Payload (ESP) Typically, in an IP network packet, the ESP header is placed after the IP header . The components of an ESP header include sequence number, payload data, padding, next header, an integrity check and sequenced numbers.

IPSec uses two distinct protocols, Authentication Header (AH) and Encapsulating Security Payload (ESP), which are defined by the IETF. … The ESP protocol provides data confidentiality (encryption) and authentication (data integrity, data origin authentication, and replay protection).

Encapsulating Security Payload (ESP) is a member of the Internet Protocol Security (IPsec) set of protocols that encrypt and authenticate the packets of data between computers using a Virtual Private Network (VPN) .