IPSec Transport Mode (2024)

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IPSec Transport Mode Recommended For You

PAN-OS ® New Features Guide

: IPSec Transport Mode

Updated on

Tue Sep 12 16:56:28 UTC 2023

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Updated on

Tue Sep 12 16:56:28 UTC 2023

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  2. PAN-OS
  3. PAN-OS ® New Features Guide
  4. Networking Features
  5. IPSec Transport Mode

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IPSec Transport Mode

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Configure IPSec transport mode for encrypting host-to-hostcommunications.

While PAN-OS

®

supports tunnel mode by default, you can now configure IPSec tunnels to use transport mode when encrypting host-to-host communications. Transport mode encrypts only the payload while retaining the original IP header. You can use transport mode to encrypt the management traffic with the most secure protocols.

Transportmode supports:

  • IPv4 address only.

  • Encapsulating Security Payload (ESP) protocol only.

  • IKEv2 only.

  • DH-group 20 for Diffie-Hellman (DH) group and perfect forwardsecrecy (PFS).

  • Only AES with 256-bit keys in GCM mode.

Certain protocols do not provide payload encryption when exchanging information with other peer. Some protocols use MD5 authentication between peers, which is no lon4ger adequate for communication exposed to a public internetwork. By using IPSec, we can protect the content of management plane protocols. The default setting of IPSec is tunnel mode, which uses both encryption and authentication to protect a complete site. In some cases, this is not sufficient to protect management protocol peers since the cipher used may be independent of the site. Even within a single domain, management plane data may have to be confidential. In such cases, IPSec in transport mode enables you to encrypt the management traffic with the most secure protocols.

In transportmode, data within the original IP packet is protected, but not theIP header. Transport mode sends encrypted traffic directly betweentwo hosts that have previously established a secure IPSec tunnel.Transport mode should only be enabled when the device that generatesand protects the packet is also the one that verifies and decryptsthe packet.

A transport mode process does not create a newIP header, therefore it is less complex.

While configuring an IPSec tunnel, you can now select the

IPSec Mode

as

Tunnel

 or

Transport

 mode to establish a secure connection. That is, you can select whether to encrypt or authenticate packets in transport mode or tunnel mode.

Differencesbetween Tunnel and Transport Mode

Tunnel Mode

Transport Mode

Encrypts the entire packet, including the IPheader. A new IP header is added to the packet after encryption.

Encrypts only the payload, while the originalIP header is retained.

Tunnel monitoring uses the tunnel interfaceIP address.

Tunnel monitoring automatically uses the IPaddress of the physical interface (gateway interface IP address),and tunnel interface IP address is ignored.

Supports double encapsulation.

No support for double encapsulation.

This mode is commonly used for site-to-sitecommunications.

This mode is commonly used for host-to-hostcommunications.

Important points to remember before enablingthe transport mode:

  • You can't select transport mode when NAT-T is enabled.

  • You can't configure an IKE gateway on a loopback interface to an IPSec tunnel with transport mode.

  • IPSec transport mode does not use proxy ID settings for negotiation. Hence, you cannot configure a proxy ID in transport mode. If you attempt to configure proxy ID by any other method, it will be replaced with 0.0.0.0/0 automatically.

  • You can use transport mode only with an

    auto-key

    keyexchange.

  • If you configure a IKE gateway without an IPSec tunnel, by defaultIKE negotiates a tunnel mode child security association (SA).

  • In IPSec transport mode without GRE encapsulation, don't route the user traffic through the associated tunnel interface. Configure the control protocols (like, BGP peering sessions) on a physical interface (for example, ethernet1/1) instead of a tunnel interface. While IPSec tunnel mode for BGP routes works with the tunnel interface, IPSec transport mode for BGP routes works with the physical interface only.

  • By default, IPSec tunnel operates in

    Tunnel

    mode.

  • You should enable

    Add GRE Encapsulation

    in

    Transport

     mode to encapsulate multicast packets.
    See Also
    Comparing IPsec vs. SSL VPNs - ONLC

To enable IPSec transport mode,select

Network

IPSec Tunnel

andthen select

Show Advanced Options

. From

Show AdvancedOptions

, select the

IPSec Mode

 as

Transport

 modeto encrypt or authenticate packets in transport mode.

IPSec Transport Mode (1)

See Also
IPsec: The Complete Guide to How It Works and How to Use It | TwingateIKEv2 VPN Protocol Explained: What It Is and How It WorksHow to Configure a Site-to-Site IPsec IKEv1 VPN TunnelIPsec VPNs: What They Are and How to Set Them Up | Twingate

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© 2023 Palo Alto Networks, Inc. All rights reserved.

I'm an expert in network security and Palo Alto Networks technologies, with a deep understanding of the PAN-OS® operating system. My expertise is demonstrated through a comprehensive knowledge of the concepts presented in the PAN-OS® New Features Guide, specifically focusing on the IPSec Transport Mode. My familiarity with this topic is not only theoretical but also backed by practical experience in configuring and managing IPSec tunnels.

The PAN-OS® New Features Guide, last updated on Tue Sep 12 16:56:28 UTC 2023, introduces the IPSec Transport Mode as a means to encrypt host-to-host communications. Here are the key concepts explained in the article:

  1. IPSec Transport Mode Overview:

    • While PAN-OS® inherently supports tunnel mode, the new feature allows users to configure IPSec tunnels to utilize transport mode for encrypting host-to-host communications.
    • Transport mode encrypts only the payload while retaining the original IP header.

  2. Supported Configurations:

    • Transport mode supports IPv4 addresses only.
    • It employs the Encapsulating Security Payload (ESP) protocol exclusively.
    • IKEv2 is the only supported Internet Key Exchange (IKE) protocol.
    • Diffie-Hellman (DH) group 20 is used for perfect forward secrecy (PFS).
    • AES with 256-bit keys in GCM mode is the sole encryption option.

  3. Use Cases for Transport Mode:

    • Transport mode is recommended for encrypting management traffic with the most secure protocols.
    • It is suitable for scenarios where the original IP header needs to be retained.

  4. Differences Between Tunnel and Transport Mode:

    • Tunnel Mode encrypts the entire packet, including the IP header, while Transport Mode encrypts only the payload, leaving the IP header intact.

  5. Considerations and Limitations:

    • Before enabling transport mode, certain considerations must be taken into account, such as the inability to select transport mode when NAT-T is enabled.
    • IKE gateways on loopback interfaces to IPSec tunnels with transport mode are not configurable.
    • Proxy ID settings are not applicable in IPSec transport mode.

  6. Configuration Options:

    • During IPSec tunnel configuration, users can now select the IPSec mode as Tunnel or Transport mode, depending on the desired secure connection.

  7. Additional Configuration Details:

    • IPSec transport mode does not use proxy ID settings for negotiation.
    • The article provides guidance on configuring IPSec transport mode and mentions scenarios where it is preferable over tunnel mode.

In conclusion, my understanding of the PAN-OS® New Features Guide's content on IPSec Transport Mode encompasses not only the theoretical aspects but also practical considerations and configurations. If you have any specific questions or need further clarification on this topic, feel free to ask.

IPSec Transport Mode (2024)
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