firewall

This document defines a data model for Access Control Lists (ACLs). An ACL is a user-ordered set of rules used to configure the forwarding behavior in a device. Each rule is used to find a match on a packet and define actions that will be performed on the packet.

This document summarizes an operator's perception of the benefits that may be provided by intermediary devices that execute functions beyond normal IP forwarding. Such intermediary devices are often called "middleboxes".

RFC 3234 defines a taxonomy of middleboxes and issues in the Internet. Most of those middleboxes utilize or modify application- layer data. This document primarily focuses on devices that observe and act on information carried in the transport layer, and especially information carried in TCP packets.

The IAB published RFC 7624 in response to several revelations of pervasive attacks on Internet communications. This document considers the implications of protocol designs that associate metadata with encrypted flows. In particular, it asserts that designs that share metadata only by explicit actions at the host are preferable to designs in which middleboxes insert metadata.

This document discusses both use cases and operational experience with Multipath TCP (MPTCP) in real networks. It lists several prominent use cases where Multipath TCP has been considered and is being used. It also gives insight to some heuristics and decisions that have helped to realize these use cases and suggests possible improvements.

The Internet is structured to be an open communications medium. This openness is one of the key underpinnings of Internet innovation, but it can also allow communications that may be viewed as undesirable by certain parties. Thus, as the Internet has grown, so have mechanisms to limit the extent and impact of abusive or objectionable communications. Recently, there has been an increasing emphasis on "blocking" and "filtering", the active prevention of such communications. This document examines several technical approaches to Internet blocking and filtering in terms of their alignment with the overall Internet architecture. When it is possible to do so, the approach to blocking and filtering that is most coherent with the Internet architecture is to inform endpoints about potentially undesirable services, so that the communicants can avoid engaging in abusive or objectionable communications. We observe that certain filtering and blocking approaches can cause unintended consequences to third parties, and we discuss the limits of efficacy of various approaches.

The Port Control Protocol (PCP) anycast addresses enable PCP clients to transmit signaling messages to their closest PCP-aware on-path NAT, firewall, or other middlebox without having to learn the IP address of that middlebox via some external channel. This document establishes one well-known IPv4 address and one well-known IPv6 address to be used as PCP anycast addresses.

This document discusses point-to-point and multi-endpoint topologies used in environments based on the Real-time Transport Protocol (RTP). In particular, centralized topologies commonly employed in the video conferencing industry are mapped to the RTP terminology.

The Internet Architecture Board (IAB) through its IP Stack Evolution program, the Internet Society, and the Swiss Federal Institute of Technology (ETH) Zurich hosted the Stack Evolution in a Middlebox Internet (SEMI) workshop in Zurich on 26-27 January 2015 to explore the ability to evolve the transport layer in the presence of middlebox- and interface-related ossification of the stack. The goal of the workshop was to produce architectural and engineering guidance on future work to break the logjam, focusing on incrementally deployable approaches with clear incentives to deployment both on the endpoints (in new transport layers and applications) as well as on middleboxes (run by network operators). This document summarizes the contributions to the workshop and provides an overview of the discussion at the workshop, as well as the outcomes and next steps identified by the workshop. The views and positions documented in this report are those of the workshop participants and do not necessarily reflect IAB views and positions.

This document specifies a new Port Control Protocol (PCP) functional element: the PCP proxy. The PCP proxy relays PCP requests received from PCP clients to upstream PCP server(s). A typical deployment usage of this function is to help establish successful PCP communications for PCP clients that cannot be configured with the address of a PCP server located more than one hop away.

This document describes several Network Address Translator (NAT) traversal techniques that were considered to be used for establishing the RTP media flows controlled by the Real-Time Streaming Protocol (RTSP). Each technique includes a description of how it would be used, the security implications of using it, and any other deployment considerations it has. There are also discussions on how NAT traversal techniques relate to firewalls and how each technique can be applied in different use cases. These findings were used when selecting the NAT traversal for RTSP 2.0, which is specified in a separate document.

This specification allows HTTP CONNECT requests to indicate what protocol is intended to be used within the tunnel once established, using the ALPN header field.

This document describes a way to avoid IP fragmentation of large Internet Key Exchange Protocol version 2 (IKEv2) messages. This allows IKEv2 messages to traverse network devices that do not allow IP fragments to pass through.

This document describes the behavior of signaling intermediaries in Real-Time Communication (RTC) deployments, sometimes referred to as Session Border Controllers (SBCs), when performing Hosted NAT Traversal (HNT). HNT is a set of mechanisms, such as media relaying and latching, that such intermediaries use to enable other RTC devices behind NATs to communicate with each other.

This document is non-normative and is only written to explain HNT in order to provide a reference to the Internet community and an informative description to manufacturers and users.

Latching, which is one of the HNT components, has a number of security issues covered here. Because of those, and unless all security considerations explained here are taken into account and solved, the IETF advises against use of the latching mechanism over the Internet and recommends other solutions, such as the Interactive Connectivity Establishment (ICE) protocol.

In today's Internet, the need for firewalls is generally accepted in the industry, and indeed firewalls are widely deployed in practice. Unlike traditional firewalls that protect network links, host firewalls run in end-user systems. Often the result is that software may be running and potentially consuming resources, but then communication is blocked by a host firewall. It's taken for granted that this end state is either desirable or the best that can be achieved in practice, rather than (for example) an end state where the relevant software is not running or is running in a way that would not result in unwanted communication. In this document, we explore the issues behind these assumptions and provide suggestions on improving the architecture going forward.