1,617 research outputs found
Preventing Distributed Denial-of-Service Attacks on the IMS Emergency Services Support through Adaptive Firewall Pinholing
Emergency services are vital services that Next Generation Networks (NGNs)
have to provide. As the IP Multimedia Subsystem (IMS) is in the heart of NGNs,
3GPP has carried the burden of specifying a standardized IMS-based emergency
services framework. Unfortunately, like any other IP-based standards, the
IMS-based emergency service framework is prone to Distributed Denial of Service
(DDoS) attacks. We propose in this work, a simple but efficient solution that
can prevent certain types of such attacks by creating firewall pinholes that
regular clients will surely be able to pass in contrast to the attackers
clients. Our solution was implemented, tested in an appropriate testbed, and
its efficiency was proven.Comment: 17 Pages, IJNGN Journa
Steganographer Identification
Conventional steganalysis detects the presence of steganography within single
objects. In the real-world, we may face a complex scenario that one or some of
multiple users called actors are guilty of using steganography, which is
typically defined as the Steganographer Identification Problem (SIP). One might
use the conventional steganalysis algorithms to separate stego objects from
cover objects and then identify the guilty actors. However, the guilty actors
may be lost due to a number of false alarms. To deal with the SIP, most of the
state-of-the-arts use unsupervised learning based approaches. In their
solutions, each actor holds multiple digital objects, from which a set of
feature vectors can be extracted. The well-defined distances between these
feature sets are determined to measure the similarity between the corresponding
actors. By applying clustering or outlier detection, the most suspicious
actor(s) will be judged as the steganographer(s). Though the SIP needs further
study, the existing works have good ability to identify the steganographer(s)
when non-adaptive steganographic embedding was applied. In this chapter, we
will present foundational concepts and review advanced methodologies in SIP.
This chapter is self-contained and intended as a tutorial introducing the SIP
in the context of media steganography.Comment: A tutorial with 30 page
What if an SQL Statement Returned a Database?
Every SQL statement is limited to return a single, possibly denormalized,
table. This design decision has far reaching consequences. (1.) for databases
users in terms of slow query performance, long query result transfer times,
usability-issues of SQL in web applications and object-relational mappers. In
addition, (2.) for database architects it has consequences when designing query
optimizers leading to logical (algebraic) join enumeration effort, memory
consumption for intermediate result materialization, and physical operator
selection effort. So basically, the entire query optimization stack is shaped
by that design decision. In this paper, we argue that the single-table
limitation should be dropped. We extend the SELECT-clause of SQL by a keyword
'RESULTDB' to support returning a result database. Our approach has clear
semantics, i.e. our extended SQL returns subsets of all tables with only those
tuples that would be part of the traditional (single-table) query result set,
however without performing any denormalization through joins. Our SQL-extension
is downward compatible. Moreover, we discuss the surprisingly long list of
benefits of our approach. First, for database users: far simpler and more
readable application code, better query performance, smaller query results,
better query result transfer times. Second, for database architects, we present
how to leverage existing closed source systems as well as change open source
database systems to support our feature. We propose a couple of algorithms to
integrate our feature into both closed-source as well as open source database
systems. We present an initial experimental study with promising results
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