Automated software attack recovery using rollback and huddle

While research into building robust and survivable networks has steadily intensified in recent years, similar efforts at the application level and below have focused primarily on attack discovery, ignoring the larger issue of how to gracefully recover from an intrusion at that level. Our work attempts to bridge this inherent gap between theory and practice through the introduction of a new architectural technique, which we call rollback and huddle. Inspired by concepts made popular in the world of software debug, we propose the inclusion of extra on-chip hardware for the efficient storage and tracing of execution contexts. Upon the detection of some software protection violation, the application is restarted at the last known safe checkpoint (the rollback part). During this deterministic replay, an additional hw/sw module is then loaded that can increase the level of system monitoring, log more detailed information about any future attack source, and potentially institute a live patch of the vulnerable part of the software executable (the huddle part). Our experimental results show that this approach could have a practical impact on modern computing system architectures, by allowing for the inclusion of low-overhead software security features while at the same time incorporating an ability to gracefully recover from attack.     

Movement-based checkpointing and logging for failure recovery of database applications in mobile environments

In this paper, we present an efficient failure recovery scheme for mobile database applications based on movement-based checkpointing and logging. Current approaches take checkpoints periodically without regard to the mobility behavior of mobile users. Our movement-based checkpointing scheme takes a checkpoint only after a threshold of mobility handoffs has been exceeded. The optimal threshold is governed by the failure rate, log arrival rate, and the mobility rate of the mobile host. This allows the tuning of the checkpointing rate on a per-user basis. We identify the optimal movement threshold which will minimize the recovery cost per failure as a function of the mobile node’s mobility rate, failure rate and log arrival rate. We derive the mobile database application recoverability, i.e., the probability that the recovery can be done by a specified recovery time deadline. Numeric data are presented to demonstrate the feasibility of our approach with its applicability given.     

基于检查点算法的网格计算容错机制研究

文章设计了一个基于网格计算的任务迁移与恢复模型，指出了该模型的各模块功能架构．并进一步分析和比较了该模型容错的检查点存储方式及其信息编码算法，最后通过实现一个基于Checksum算法的容错CG求解器实例表明相关理论的有效性。     

Unix进程检查点设置关键技术

Unix进程的检查点设置是实现分布/并行系统容错、重播调试、进程迁移、系统模拟和作业切换等功能的基础。该论文主要论述UNIX进程检查点基本信息的保存与恢复、文件检查点、检查点信息的优化等关键技术,最后介绍Libckpt、Condor以及自行设计的Libcsm等检查点设置工具。     

分布式冗余管理系统可靠性的设计与实现

该文首先对所研究的分布式冗余服务管理系统进行了描述,分析了该系统的可靠性,然后建立了基于主从备份的分布式管理可靠性模型,对模型的可用性进行了定量分析,最后详细阐述了实现过程中所采用的故障检测技术。     

PDES中乐观时间同步的时空损耗研究

并行离散事件仿真对复杂大规模动态系统的研究以及探索其长远的应用提供了便利，近年来日益成为研究的热点。然而时间同步管理是影响并行离散事件仿真系统高效运行的重要因素之一。乐观的同步是采用检测和回退机制，允许逻辑进程积极的处理本地事件。一旦出现同步错误则利用回退机制从错误中恢复到较早状态，然后再恢复执行。这一切都是通过基于检查点状态保存重建机制来实现的，因而状态保存及状态重建必然伴随着时间和空间的损耗。该文深入研究了在乐观同步机制下，仿真执行时间和内存空间的损耗与检查点间隔之间的关系，并通过推理计算给出了检查点间隔的最优取值范围。     

融合容错需求和资源约束的云容错服务适配方法

云计算环境下,失效成为一种常态行为,可靠性保障能力不足不仅成为云计算应用推广的主要障碍,而且还促使云计算环境下的容错服务研究成为一个亟待解决的问题。针对目前云计算容错服务研究中存在的用户容错需求定义无法直接反映用户关心的可靠性问题,以及云容错服务供应商资源得不到灵活利用等问题,提出了一种融合容错需求和资源约束的云容错服务适配方法。从用户的角度,以组件为单位,基于可靠性对用户的容错需求进行定义。从云容错服务供应商的角度,分别在其资源充足和资源不足的情况下研究最佳的容错服务适配方法,并使用最优化理论求解该适配方法下的容错服务。实验结果表明,所提出的容错服务适配方法生成的容错服务能更好地满足用户和云容错服务供应商的需求。     

软件内建自测试中测试点的设置及个数的研究

软件内建自测试思想来自于硬件内建自测试。其中测试点设置是软件内建自测试系统的核心模块之一,主要借助程序插装技术收集动态测试信息和控制程序流程。具体讨论了插装库的设计、实现以及测试点个数的统计。     

双机容错系统FTDC的设计与实现

给出了一种利用现有计算机和少量必要的硬件,以容错管理软件为主要手段实现的低成本双机容错系统,主要介绍了该机的容错设计、容错管理软件的实现以及关键技术等问题。     

The Stone Guest: How Does pH Affect Binding Properties of PD-1/PD-L1 Inhibitors?

The interaction between programmed cell death-1 (PD-1) and its ligand PD−L1 activates a coinhibitory signal that blocks T-cell activation, promoting the immune escape process in the tumor microenvironment. Development of monoclonal antibodies targeting and inhibiting PD-1/PD−L1 interaction as anticancer immunotherapies has proved successful in multiple clinical settings and for various types of cancer. Notwithstanding, limitations exist with the use of these biologics, including drug resistance and narrow therapeutic response rate in a majority of patients, that demand for the design of more efficacious small molecule-based immunotherapies. Alteration of pH in the tumor microenvironment is a key factor that is involved in promoting drug resistance, tumor survival and progression. In this study, we have investigated the effect of pH shifts on binding properties of distinct classes of PD−L1 inhibitors, including macrocyclic peptide and small molecules. Results expand structure-activity relationships of PD−L1 inhibitors, providing insights into structural features and physicochemical properties that are useful for the design of ligands that may escape a drug resistance mechanism associated to variable pH conditions of tumor microenvironment.