防护性DNS服务关键技术研究综述

域名系统(domain name system,DNS)作为互联网资源的名字标识服务,提供了从域名到IP地址的查询转换功能,是用户访问互联网应用的入口,也是用户侧安全威胁感知与防御的关键点。用户侧常见的DNS滥用及相关安全威胁有:网络钓鱼、域名不良应用、恶意软件以及利用DNS进行攻击等。防护性DNS(protective DNS,PDNS)服务是一种利用DNS协议和架构的网络安全防护技术,通过对DNS查询进行威胁检测与处置,能够从源头上阻止用户对网络钓鱼网站、不良网站、恶意软件的访问。目前学界对PDNS服务还缺少系统的介绍与研究。对PDNS已有研究工作、应用现状及架构与功能进行系统梳理,对PDNS所涉及的关键技术进行系统综述,主要包括域名威胁处置技术、DNS异常检测技术、威胁情报管理技术和数据存储管理技术,分析PDNS目前面临的问题与挑战,并对PDNS未来发展趋势与研究方向提出了展望。

基于威胁情报的DNS助力医院网络安全建设实践

目的利用威胁情报和域名解析系统(DNS)加强医院网络安全。方法在医院互联网出口配置基于威胁情报的安全DNS策略,让医院终端及互联网信息系统通过安全DNS访问互联网。结果应用安全DNS后,医院对外的恶意域名访问被100%拦截,能有效拦截和阻断高级持续性威胁。结论通过应用基于威胁情报的安全DNS,提升了医院对网络安全漏洞的定位能力,缩短了响应时间,降低了处置成本,这对于做好医院网络安全加固和提升医院安全整体水平具有借鉴意义。

多校区校园网一体化DNS网络架构研究

高校多校区一体化管理中,校区间人员流动频繁,如何保证学校师生在不同校区获得一致的上网体验成为一个难题。除了加快建设多活数据中心,实现重要信息系统的容灾备份体系之外,网络基础设施服务域名系统(Domain Name System,DNS)的一体化部署也面临新挑战。以河海大学南京校区和常州校区为例,通过多活容灾网络架构等技术手段部署一体化智能DNS服务,有效解决网络拥塞和信息系统访问瓶颈的问题,同时提升DNS管理的便捷性和服务的安全可靠性,对相关应用场景具有一定参考价值。

湍流燃烧二阶矩模型DNS检验研究进展的回顾

现有的湍流燃烧模型中,有的缺乏普适性,也有的用于大涡模拟的计算量太大.一种基于湍流流动模拟思路的统计矩方法被提出来,称为二阶矩(second-order moment,SOM)燃烧模型,用于非预混射流火焰和旋流火焰的雷诺平均模拟(Reynolds-averaged Navier-Stokes modeling,RANS)和大涡模拟(large-eddy simulation,LES),以及钝体后方预混火焰的大涡模拟,已经得到实验结果的良好检验.进一步的研究是该模型的直接数值模拟(direct numerical simulation,DNS)检验.本文对作者以及文献中报导的SOM模型DNS检验的研究进展进行了回顾.

基于RF-RNN模型的DNS隐蔽信道检测方法

为提高检测隐蔽信道的灵敏度,提出一种基于随机森林(Random Forest,RF)和循环神经网络(Recurrent Neural Network,RNN)的域名系统(Domain Name System,DNS)隐蔽信道检测方法。该方法采用域名检测作为主要手段,使用RF模型对域名进行分类,通过深度学习方法挖掘更高阶的特征表示。实验结果表明,与单一模型相比,该方法在检测准确性和健壮性方面均取得了显著提升。

DNS信道传输加密技术:现状、趋势和挑战

DNS作为重要的互联网基础设施,其明文传输的特点带来很多隐私安全风险.DoH、DoT、DoQ等DNS信道传输加密技术致力于防止DNS数据被泄露或篡改,并保证DNS消息来源的可靠性.首先从DNS消息格式、数据存储和管理、系统架构和部署等6个方面分析明文DNS存在的隐私安全问题,并对已有的相关技术和协议进行总结.其次分析DNS信道传输加密技术的实现原理及应用现状,进而基于多角度评测指标对各加密协议在不同网络条件下的性能表现进行讨论.同时通过填充机制的局限性、加密流量识别和基于指纹的加密活动分析等方向探讨DNS信道传输加密技术的隐私保护效果.此外从部署规范、恶意流量对加密技术的利用和攻击、隐私和网络安全管理之间的矛盾,以及加密后影响隐私安全的其他因素等方面总结DNS信道传输加密技术存在的问题、挑战和相关解决方案.最后总结加密DNS服务的发现、递归解析器到权威服务器之间的加密、服务器端的隐私保护、基于HTTP/3的DNS等后续需要着重关注的研究方向.

DNS核心稳定训练结合局部针刺运动对脑卒中后偏瘫患者步行及姿势控制能力的影响

目的:探讨动态神经肌肉稳定技术(Dynamic Neuromuscular Stabilization,DNS)下的核心稳定训练结合局部针刺运动方案对脑卒中后偏瘫患者步行及姿势控制能力的影响。方法:选取2022年3月~2022年9月在郴州市第一人民医院就诊的脑卒中患者90例,按随机数字表分为对照组(n=45)和观察组(n=45),对照组采用常规康复训练,观察组在此基础上增加DNS核心稳定训练结合局部针刺运动疗法。治疗8周后,对比并分析治疗前后两组患者步态时空参数中步长、步速、步频参数;步态时相参数中双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、步行周期参数;脑卒中患者姿势控制量表(Posture assessment of stoke scale,PASS)量表、Tinnetti(Performance-Oriented Assessment of Mobility)量表及Fugl-Meyer下肢运动功能(FMA-LE)量表评分数据。结果:治疗后,两组步长、步速、步频参数、双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、Tinnetti评分、PASS评分及FMA评分均显著高于治疗前(P<0.05),步行周期显著低于治疗前(P<0.05),且观察组治疗后步长、步速、步频参数、双支撑相占步态周期百分比、患侧单支撑相占步态周期百分比、PASS评分、Tinnetti评分及FMALE评分均显著高于对照组(P<0.05),步行周期则低于对照组(P<0.05)。结论:DNS核心稳定训练结合局部针刺运动可提高脑卒中后偏瘫患者核心稳定及姿势控制能力,改善步行功能。

递归侧DNS安全研究与分析

因特网用户在访问网络应用前都需要通过DNS进行解析,DNS安全是保障网络正常运行的第1道门户,如果DNS的安全不能得到有效保证,即使网络其他系统安全防护措施级别再高,攻击者也可以通过攻击DNS系统使网络无法正常使用.目前DNS恶性事件仍有上升趋势,DNS攻击检测和防御技术的发展仍不能满足现实需求.从直接服务用户DNS请求的递归解析服务器视角出发,将DNS安全事件通过两种分类方法,全面梳理和总结DNS工作过程中面临的安全问题,包括由攻击或系统漏洞等引起各类安全事件,各类安全事件的具体检测方法,各类防御保护技术.在对各类安全事件、检测和防御保护技术总结的过程中,对相应典型方法的特点进行分析和对比,并对未来DNS安全领域的研究方向进行展望.

一种基于DNS的零信任增强认证系统设计

针对当前大量HTTPS应用复用证书存在安全风险问题,借鉴了零信任模型中安全策略动态授权的思路,提出了一种基于现有互联网基础设施DNS来扩展增强认证功能的方案,通过在现有DNS权威服务器上额外配置增强的认证信息来对HTTPS访问请求进行动态认证,从而能实时验证当前HTTPS证书的安全状态。该方案通过可信易得的DNS基础设施解决了当前普遍存在的HTTPS证书复用带来的安全问题,是一种灵活高效并且可扩展的零信任安全增强认证架构。

Adsorption,in vitro digestion and human gut microbiota regulation characteristics of three Poria cocos polysaccharides

Poria cocos(PC)is a famous traditional Chinese medicine(TCM)and a widely used healthcare ingredient,which has antiobesity,enhancing immunity and improving sleep effects.Traditionally,only water-soluble poria polysaccharide(WSP)is extracted and applied for clinical application,while insoluble polysaccharide(alkali-soluble poria polysaccharide,ASP)is discarded as herb residue.However,the whole PC has also been historically utilized as functional herbal food.Considering the beneficial role of dietary fiber and the traditional use of PC,ASP may also contribute substantially to the therapy function of PC.Compared to WSP,little attention has been paid to ASP and ASP modified product carboxymethyl poria polysaccharide(CMP)which has been used as an antitumor adjuvant drug.In this study,the oil,cholesterol,metal ions and polyphenols adsorption ability,in vitro simulated digestive and the gut microbiota fermentation characteristics of WSP,ASP and CMP were studied to evaluate the functional values of three P.cocos polysaccharides(PCPs).The results showed that all three PCPs had good adsorption capacity on cholesterol,polyphenols and metal ions(Cd^(2+)/Zn^(2+)/Mg^(2+)),among which ASP showed the highest capacity than WSP and CMP.The adsorption capacity of all three PCPs on heavy metal ions(Cd^(2+)/Zn^(2+))was stronger than that of non-heavy metal ions(Mg^(2+));The in vitro digestibility of all three PCPs was very low,but WSP was slightly higher than ASP and CMP;Moreover,the indigestible residue of all three PCPs could improve the richness and diversity of gut microbiota,among which ASP had the greatest influence.In general,ASP and CMP could significantly promote the proliferation of some probiotics and inhibit the growth of some harmful bacteria.The gut microbiota diversity of CMP was reduced,but the richness of probiotics,especially Parabacteroides distasonis was significantly enhanced compared with the ASP group,and the growth of harmful bacteria Klebsiella pneumoniae was inhibited after CMP treatment.The short-chain fatty acids(SCFAs)analysis results showed that all three PCPs could significantly promote the production of acetic acid,propionic acid and the total acid content compared with blank control group,and SCFAs producing activity was positively correlated with the proliferative capacity of probiotics.Taken together,the good adsorption characteristics and gut microbiota regulatory activity of ASP may lay foundation for its lipid-lowering and immune-improving function.Additionally,the probiotic effect of CMP and ASP indicated that except for only use the water extract of PC in clinic,CMP and ASP also can be used in healthcare to take full advantage of this valuable medicine.

The interventional effect of Polygonatum cyrtonema Hua polysaccharide on atherosclerosis in mice of different sexes

In the present study,we investigated the intervention effects of a purified Polygonatum cyrtonema polysaccharide(PCP)on high-fat diet(HFD)-induced atherosclerosis in male and female LDLr-/-mice.Results showed that HFD caused severe dyslipidemia,atherosclerotic lesions,oxidative damages and inflammation in male and female mice,and these effects seemed to be more pronounced in males than in females.However,the above variations could be dose-dependently reversed by PCP treatment,and the intervention effects on males were greater than those on females.Nuclear factor kappa-B(NF-κB),mitogen-activated protein kinase(MAPKs)and protein kinase B(Akt)are 3 pivotal signaling pathways mediating the development of atherosclerosis.Consistently,PCP was also found to significantly decrease the phosphorylation of p65,p38,extracellular-regulated kinase 1/2(ERK1/2)and Akt,and increase the protein expression of inhibitor of NF-κB(IκB)in the aortas of male and female mice induced by HFD.Taken together,these findings indicated that PCP could be effective for the prevention of atherosclerosis,and the intervention effect of PCP on male mice was more obvious than that of female mice.

Protective mechanism of Coprinus comatus polysaccharide on acute alcoholic liver injury in mice,the metabolomics and gut microbiota investigation

Coprinus comatus polysaccharide(CCP)has significant hepatoprotective effect.To explore hepatoprotective mechanism of CCP,the study analyzed preventive effect of CCP on acute alcoholic liver injury in mice by histopathological examination and biochemical analysis.Simultaneously,hepatoprotective mechanism was also analyzed in conjunction with metabolomics and proliferation of gut microbiota.The results showed that CCP significantly decreased alanine aminotransferase(ALT),aspartate aminotransferase(AST)and triglyceride(TG)levels in serum of alcoholic liver disease(ALD)mice.Histopathological examination showed that CCP can significantly improve liver damage.Metabolomics results showed that there were significant differences in the level of metabolites in liver tissue of control group,ALD group and CCP group,including taurine,xanthosine,fumaric acid and arachidonic acid,among others.Metabolites pathways analysis showed that hepatoprotective effect of CCP was related to energy metabolism,biosynthesis of unsaturated fatty acids,amino acids metabolism and lipid metabolism.Additionally,CCP inhibited an increase in the number of Clostridium perfringens,Enterobacteriaceae and Enterococcus,and a decrease in the number of Lactobacillus and Bifidobacterium in the gut of ALD mice.All these findings suggested that CCP treatment reversed the phenotype of ethanol-induced liver injury and the associated metabolites pathways.

Structure and immunomodulatory activity of Lentinus edodes polysaccharides modified by probiotic fermentation

Plant-based fermentations provide an untapped source for novel biotechnological applications.In this study,a probiotic named Lactobacillus fermentum 21828 was introduced to ferment Lentinus edodes.Polysaccharides were extracted from fermented and non-fermented L.edodes and purified via DEAE-52 and Sephadex G-100.The components designated F-LEP-2a and NF-LEP-2a were analyzed by FT-IR,HPGPC,HPAEC,SEM,GC-MS and NMR.The results revealed that probiotic fermentation increased the molecular weight from 1.16×10^(4) Da to 1.87×10^(4) Da and altered the proportions of glucose,galactose and mannose,in which glucose increased from 45.94%to 48.16%.Methylation analysis and NMR spectra indicated that F-LEP-2a and NF-LEP-2a had similar linkage patterns.Furthermore,their immunomodulatory activities were evaluated with immunosuppressive mice.NF-LEP and F-LEP improved immune organ indices,immunoglobulin(Ig G and Ig M)and cytokines concentrations;restored the antioxidation capacity of liver;and maintained the balance of gut microbiota.F-LEP displayed better moderating effects on the spleen index,immunoglobulin,cytokines and the diversity of gut microbiota than NF-LEP(200,400 mg/kg).Our study provides an efficient and environment-friendly way for the structural modification of polysaccharides,which helps to enhance their biological activity and promote their wide application in food,medicine and other fields.

Sulfated Cyclocarya paliurus polysaccharides exert immunomodulatory potential on macrophages via Toll-like receptor 4 mediated MAPK/NF-κB signaling pathways

The biological activity of plant polysaccharides can be enhanced by sulfated modification.In this study,the immunomodulatory effect of sulfated Cyclocarya paliurus polysaccharides(SCP3)on macrophages RAW264.7 and its potential molecular mechanism were investigated.Results showed that SCP3 at 25-100μg/m L increased viability and improved phagocytosis of RAW264.7 cells.Meanwhile,SCP3 could activate mitogen-activated protein kinase(MAPK)and nuclear factor kappa B(NF-κB)signaling pathways,which increased the phosphorylation of Erk1/2,JNK,p38 and NF-κB p65,promoting secretion of cytokines tumor necrosis factorα(TNF-α),interleukin 6(IL-6)and nitric oxide(NO)as well as the production of reactive oxygen species(ROS).In addition,Toll-like receptor 4(TLR4)receptor inhibitors were able to block the production of NO and TNF-αby SCP3-stimulated macrophages.Based on Western blot analysis and validation using specific inhibitors against MAPK and NF-κB signaling pathways,the results demonstrated that SCP3 induced macrophages activation and enhanced TNF-αand NO production via TLR4-mediated MAPK and NF-κB pathways.In summary,SCP3 has significant immunomodulatory potential.The underlying molecular mechanism was that SCP3 activates macrophages via TLR4 receptors to promote ROS production,which in turn activates the downstream MAPK/NF-κB signaling pathway and then increases the secretion levels of cytokines and NO.

Hypoglycemic mechanism of Tegillarca granosa polysaccharides on type 2 diabetic mice by altering gut microbiota and regulating the PI3K-akt signaling pathwaye

Type 2 diabetes mellitus(T2DM)is a complex metabolic disease threatening human health.We investigated the effects of Tegillarca granosa polysaccharide(TGP)and determined its potential mechanisms in a mouse model of T2DM established through a high-fat diet and streptozotocin.TGP(5.1×10^(3) Da)was composed of mannose,glucosamine,rhamnose,glucuronic acid,galactosamine,glucose,galactose,xylose,and fucose.It could significantly alleviate weight loss,reduce fasting blood glucose levels,reverse dyslipidemia,reduce liver damage from oxidative stress,and improve insulin sensitivity.RT-PCR and Western blotting indicated that TGP could activate the phosphatidylinositol-3-kinase/protein kinase B signaling pathway to regulate disorders in glucolipid metabolism and improve insulin resistance.TGP increased the abundance of Allobaculum,Akkermansia,and Bifidobacterium,restored the microbiota abundance in the intestinal tracts of mice with T2DM,and promoted short-chain fatty acid production.This study provides new insights into the antidiabetic effects of TGP and highlights its potential as a natural hypoglycemic nutraceutical.

Ganoderma Lucidum polysaccharide peptides protect kidney from renal ischemia reperfusion injury via counteracting oxidative stress

OBJECTIVE Ganoderma lucidum polysaccharide peptides(GLPP)have an anti-oxidant activity.The oxidative stress implicates in the pathogenesis of renal ischemia-reperfusion injury(RIRI).The objective of this study was to determine whether GLPP could attenuate RIRI via counteracting the oxidative stress.METHODS Mice subjected to uninephrectomy with the right kidney ischemia for 35 min and reperfusion for 24 hwere used to explore the protective activity of GLPP against RIRI.In GLPP-treated group,100mg·kg-1·d-1 of GLPP were intraperitoneally injected for 7dbefore the procedure.In vitro,NRK-52 Ecells subjected to hypoxia-reoxygenation(H/R)and tunicamycin were used to explore the protective effect of GLPP against oxidative stress.The mechanisms in which GLPP protected kidney from RIRI were studied using a series of physiological and molecular biological methods.RESULTS Kidneys undergone ischemia-reperfusion showed renal dysfunction and characteristic morphological changes including cellular necrosis,brush border loss,cast formation,vacuolization and tubular dilatation while these damages were significantly attenuated by GLPP treatment.The abnormal levels of MPO,MDA and SOD caused by renal ischemia-reperfusion were significantly reversed by GLPP treatment.More apoptotic cells were found in the renal ischemia-reperfusion group than the sham group whereas GLPP reduced apoptotic cells in the ischemia-reperfusion mice by21.75%(P<0.01).The GLPPs(25-1μg·mL)alleviated H/R induced cell viability loss by 20.12%(P<0.01)andΔφm dissipation by 27.3%(P<0.01)in vitro as well and its pretreatment dramatically reduced H/R and tunicamycin induced cell injury.CONCLUSION Our study found that GLPP had a protective effect on RIRI via its anti-oxidative capacity,which suggests that GLPP may be developed as a candidate drug for preventing acute kidney injury.

递归侧DNSSEC错误配置检测能力大规模探测分析

DNSSEC(domain name system security extensions)是一种域名系统(DNS,domain name system)的安全扩展协议,通过为DNS记录添加签名来增加DNS的安全性。域名递归服务器能否有效验证DNSSEC配置的正确性,并且在配置错误时返回相应的错误类型,对保障整个DNS的安全至关重要。为此,基于RFC 8914标准,选择了8种在权威侧可配置的DNSSEC错误类型,并在8个不同的子域分别配置了相应的DNSSEC错误。接下来,面向全球范围内的公共DNS服务器,筛选出其中支持DNSSEC的递归服务器作为探测对象,针对上述8个子域发起解析请求,对探测结果进行了收集、分析及可视化。探测结果表明,对于部分错误,多数支持DNSSEC的递归服务器可以正确地检测出域名的DNSSEC错误配置,并且返回相应的错误类型,如signature_expired、signature_not_valid、RRSIG_missing、DNSKEY_missing等错误。对当前全球范围内重要递归服务器检测DNSSEC错误配置的能力开展了大规模测量分析,可有效指导未来DNSSEC广泛部署中递归侧的能力建设。

基于智能DNS与反向代理实现Web应用系统IPv6网络部署与IPv4网络安全加固

基于下一代互联网核心技术IPv6具有地址空间足够大、安全性更高、服务质量更好、支持终端设备移动等特性,高校的信息化发展在逐步推进IPv6网络部署与信息系统的IPv6网络应用。然而,在高校推进应用系统的IPv6网络部署访问过程中,仍然存在部分底层网络设备不支持IPv6协议、安全设备无法做到全面管控等问题。为尽可能不改变当前学校网络架构,不影响当前学校应用系统的IPv4网络访问,提出了基于智能DNS与反向代理设备实现高校Web应用系统IPv6网络部署与访问的技术方法。该技术方法具有实现原理简单、稳定性强、安全性高、易维护等特性,通过联动部署,实现了学校应用系统的IPv6网络访问与IPv4访问安全加固,为高校校园网IPv6网络应用部署提供了参考实践。

基于多通道卷积和注意力网络的DNS隐蔽信道检测算法

域名系统(domain name system,DNS)隐蔽信道是一种利用DNS协议实现数据泄露的网络攻击手段,受到诸多高级持续性威胁(advanced persistent threat,APT)组织的青睐,给网络空间安全带来了严重威胁。针对传统机器学习方法对特征依赖性强、误报率高的问题,提出一种融合多通道卷积和注意力网络的DNS隐蔽信道检测算法。该算法基于DNS请求与响应双向流,首先将残差结构和并行卷积相结合,采用不同大小的卷积核提取并融合多尺度特征信息,实现不同感受野特征的捕获;其次引入通道注意力机制增加卷积通道关键信息的提取能力,丰富网络模型的表达能力;最后采用softmax函数实现DNS隐蔽信道的检测。实验结果表明,所提模型能有效检测DNS隐蔽信道,平均准确率、精确率和召回率分别为96.42%、97.82%和96.16%,优于传统方法。

递归-权威侧部署加密DNS协议的隐私收益评估方法及测量分析

加密DNS协议最初被设计用于保护用户和递归解析器之间(用户-递归侧)的DNS通信隐私。目前,加密DNS协议获得了广泛应用。然而,递归解析器和权威服务器之间(递归-权威侧)的DNS通信仍遭受着大量隐私威胁。历经4年的标准化进程,互联网工程任务组在2024年2月正式发布RFC 9539,提出可利用加密DNS协议来保障递归-权威侧的DNS通信隐私。聚焦于在递归-权威侧部署加密DNS协议所带来的隐私收益,提出评估互联网域名隐私收益的方法。针对243万个流行域名和4万个敏感域名,结合1058个顶级域名的区域文件,分析权威服务器所托管的域名数量,从而判定目标域名的隐私收益等级。测量结果表明,超过90%的域名可获得递归-权威侧部署加密DNS协议的隐私保护,但是6.28%的敏感域名无法从递归-权威侧部署加密DNS协议中获得隐私收益。此外,一些高流行度的域名也没有获得足够的隐私收益。相较于大型域名托管商,小型域名托管商可为域名提供更高的隐私收益。将域名部署于仅托管单个域名的权威服务器上会极大地损害递归-权威侧加密DNS协议的隐私保护效果,管理人员应重新审视域名托管服务。