Unicast UDP Usage Guidelines for Application Designers

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An Internet Heartbeat

Obtaining sound inferences over remote networks via active or passive measurements is difficult. Active measurement campaigns face challenges of load, coverage, and visibility. Passive measurements require a privileged vantage point. Even networks under our own control too often remain poorly understood and hard to diagnose. As a step toward the democratization of Internet measurement, we consider the inferential power possible were the network to include a constant and predictable stream of dedicated lightweight measurement traffic. We posit an Internet "heartbeat," which nodes periodically send to random destinations, and show how aggregating heartbeats facilitates introspection into parts of the network that are today generally obtuse. We explore the design space of an Internet heartbeat, potential use cases, incentives, and paths to deployment

Full TCP/IP for 8-Bit architectures

We describe two small and portable TCP/IP implementations fulfilling the subset of RFC1122 requirements needed for full host-to-host interoperability. Our TCP/IP implementations do not sacrifice any of TCP's mechanisms such as urgent data or congestion control. They support IP fragment reassembly and the number of multiple simultaneous connections is limited only by the available RAM. Despite being small and simple, our implementations do not require their peers to have complex, full-size stacks, but can communicate with peers running a similarly light-weight stack. The code size is on the order of 10 kilobytes and RAM usage can be configured to be as low as a few hundred bytes

ICMP: an Attack Vector against IPsec Gateways

In this work we show that the Internet Control Message Protocol (ICMP) can be used as an attack vector against IPsec gateways. The main contribution of this work is to demonstrate that an attacker having eavesdropping and traffic injection capabilities in the black untrusted network (he only sees ciphered packets), can force a gateway to reduce the Path MTU of an IPsec tunnel to a minimum, which in turn creates serious issues for devices on the trusted network behind this gateway: depending on the Path MTU discovery algorithm, it either prevents any new TCP connection (Denial of Service), or it creates major performance penalties (more than 6 seconds of delay in TCP connection establishment and ridiculously small TCP segment sizes). After detailing the attack and the behavior of the various nodes, we discuss some counter measures, with the goal to find a balance between ICMP benefits and the associated risks

ICMP: an Attack Vector against IPsec Gateways

In this work we show that the Internet Control Message Protocol (ICMP) can be used as an attack vector against IPsec gateways. The main contribution of this work is to demonstrate that an attacker having eavesdropping and traffic injection capabilities in the black untrusted network (he only sees ciphered packets), can force a gateway to reduce the Path MTU of an IPsec tunnel to a minimum, which in turn creates serious issues for devices on the trusted network behind this gateway: depending on the Path MTU discovery algorithm, it either prevents any new TCP connection (Denial of Service), or it creates major performance penalties (more than 6 seconds of delay in TCP connection establishment and ridiculously small TCP segment sizes). After detailing the attack and the behavior of the various nodes, we discuss some counter measures, with the goal to find a balance between ICMP benefits and the associated risks

Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD)

Disruptions in end-to-end path connectivity, which last longer than one retransmission timeout, cause suboptimal TCP performance. The reason for this performance degradation is that TCP interprets segment loss induced by long connectivity disruptions as a sign of congestion, resulting in repeated retransmission timer backoffs. This, in turn, leads to a delayed detection of the re-establishment of the connection since TCP waits for the next retransmission timeout before it attempts a retransmission. This document proposes an algorithm to make TCP more robust to long connectivity disruptions (TCP-LCD). It describes how standard ICMP messages can be exploited during timeout-based loss recovery to disambiguate true congestion loss from non-congestion loss caused by connectivity disruptions. Moreover, a reversion strategy of the retransmission timer is specified that enables a more prompt detection of whether or not the connectivity to a previously disconnected peer node has been restored. TCP-LCD is a TCP senderonly modification that effectively improves TCP performance in the case of connectivity disruptions. Status of This Memo This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation. This document defines an Experimental Protocol for the Internet community. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained a