Why Use IPSEC AH vs ESP? - Information Security Stack Exchange
May 25, 2015 · AH was intended only for sales to crypto-restricted customers. ESP was designed to accommodate cases where encryption is not desirable. AH was for the cases where one had to guarantee that no matter what the end-user does, enabling/adding encryption to this product would not be possible (again, within the given standard, of course).
Difference Between ESP & AH in IPsec - Cisco Learning Network
The basic difference is that ESP provides actual encryption. It encrypts the payload of the packet and protects it from snooping. AH only provides message authentication. In other words, AH only lets the receiver verify that the message is intact and unaltered, but it doesn't encrypt the message by itself.
IPSec: Using ESP after AH - Information Security Stack Exchange
Jan 24, 2017 · Thus if AH is used in a transport mode, in conjunction with ESP, AH SHOULD appear as the first header after IP, prior to the appearance of ESP. In that context, AH is applied to the ciphertext output of ESP. In contrast, for tunnel mode SAs, one can imagine uses for various orderings of AH and ESP. Also, doing authentication before encryption ...
when to use AH only? - Information Security Stack Exchange
Jun 10, 2012 · AH may be applied alone, in combination with the IP Encapsulating Security Payload (ESP) [KA97b], or in a nested fashion through the use of tunnel mode (see "Security Architecture for the Internet Protocol" [KA97a], hereafter referred …
IPSec confusion - Cisco Learning Network
From there on the IPSec SA, phase 2 tunnel comes up for the actual data. This is where AH and ESP come in. So with AH you are only making sure that the source of the data is trusted (authentication) and that the contents of the data has not changed (integrity). AH does not encrypt the data, so it is sent in clear text. ESP does provide encryption.
ipsec - Does AH in tunneling mode provide encryption?
Dec 5, 2016 · I understand that AH only provides authentication and integrity checks, but NO encryption (ESP does provide encryption). So far so good. However, reading on Tunnel / transport mode always says that tunnel mode encrypts the entire IP packet, and transport mode only encrypts the payload but leaves the headers intact.
Is there any real-world use of IPsec modes other than ESP tunnel?
Jan 16, 2017 · Authentication headers (AH) in which there is no encryption at all, but headers are authenticated so that they cannot be altered without detection. What I'm wondering is whether there is any significant real-world usage of these less-than-fully encrypted and authenticated modes of IPsec, as of 2017.
Using IPsec through NAT - Information Security Stack Exchange
Jul 12, 2017 · ESP Security Associations (SA) are unidirectional. So to communicate bidirectionally two SAs are required, on each end one SA is for inbound traffic and one for outbound traffic (and vice-versa on the other end). These SAs are identified by the protocol (ESP/AH), destination IP address and a 32-bit identifier called Security Parameters Index (SPI).
network - Why doesn't IPSec ESP protect the IP-Header?
Jan 23, 2017 · Specifically, ESP does not protect any IP header fields unless those fields are encapsulated by ESP (e.g., via use of tunnel mode). So if protecting parts of the outer IP header (and extension headers) is not a requirement, ESP basically provides the same functionality as AH. ESP may even be used without confidentiality, RFC 4303 (ESP):
When do I use IPsec tunnel mode or transport mode?
Dec 18, 2014 · Among the two parties who want to communicate, if one computer B doesn't understand IPsec, I think they have to use tunnel mode, which puts original IP and payload into ESP and delivers the packet to a device near B who knows IPsec, and that device decrypts the packet and sends the decrypted packet to computer B.