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This paper presents the design, implementation, and experimental evaluation of CMAP (Conflict Maps), a system that increases the number of successful concurrent transmissions in a wireless network, achieving higher aggregate throughput compared to networks that use carrier sense multiple access (CSMA). CMAP correctly identifies and exploits exposed(More)
This paper presents SoftRate, a wireless bit rate adaptation protocol that is responsive to rapidly varying channel conditions. Unlike previous work that uses either frame receptions or signal-to-noise ratio (SNR) estimates to select bit rates, SoftRate uses confidence information calculated by the physical layer and exported to higher layers via the(More)
This paper presents the design, implementation, analysis, and experimental evaluation of <i>speak-up</i>, a defense against <i>application-level</i> distributed denial-of-service (DDoS), in which attackers cripple a server by sending legitimate-looking requests that consume computational resources (<i>e.g</i>., CPU cycles, disk). With speak-up, a victimized(More)
Over the past few years, researchers have developed many <i>cross-layer</i> wireless protocols to improve the performance of wireless networks. Experimental evaluations of these protocols have been carried out mostly using software-defined radios, which are typically two to three orders of magnitude slower than commodity hardware. FPGA-based platforms(More)
Information about the geographic locality of IP prefixes can be useful for understanding the issues related to IP address allocation, aggregation, and BGP routing table growth. In this paper, we use traceroute data and geographic mappings of IP addresses to study the geographic properties of IP prefixes and their implications on Internet routing. We find(More)
Network intrusion detection and prevention systems are vulnerable to evasion by attackers who craft ambiguous traffic to breach the defense of such systems. A normalizer is an inline network element that thwarts evasion attempts by removing ambiguities in network traffic. A particularly challenging step in normalization is the sound detection of(More)
— The Internet's current interdomain routing protocol, BGP (Border Gateway Protocol), has two modes of operation: eBGP (external BGP), used to exchange routing information between autonomous systems, and iBGP (internal BGP), used to propagate that information within an autonomous system (AS). In a " full mesh " iBGP configuration, every router has a BGP(More)
We present Witals, a system for WiFi performance diagnosis. In Witals, a live access point diagnoses the health of the WiFi network by examining the health of the air around it. Such diagnosis is critical functionality for sysads, and is an important addition to the state of the art. In the demo we will show WiFi performance diagnosis by Witals live at(More)
—How does a dense WiFi network perform, specifically for the common case of TCP download? While the empirical answer to this question is 'poor', analysis and experimentation in prior work has indicated that TCP clocks itself quite well, avoiding contention-driven WiFi overload in dense settings. This paper focuses on measurements from a real-life use of(More)
—This paper describes a system for improving user experience when accessing overloaded web servers. While several techniques exist today to build high-capacity web servers, little attention is paid to the fact that servers often crash when faced with transient overload, causing user experience to degrade sharply when incoming load exceeds capacity. Existing(More)
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