Mitigating Coordinated Call Attacks On VoIP Networks Using Hidden Markov Model

Abstract This paper presents a 2-tier scheme for mitigating coordinated call attacks on VoIP networks. Call interaction pattern was considered using talk and salient periods in a VoIP call conversation. At the first-tier, Short Term Energy algorithm was used for call interaction feature extraction and at the second-tier Hidden Markov Model was used for caller legitimacy recognition. Data of VoIP call conversations were collated and analyzed to extract distinctive features in VoIP call interaction pattern to ascertain the legitimacy of a caller against coordinated call attacker. The performance metrics that was used are; False Error Rate (FER), Specificity, Detection Accuracy and Throughput. Several experiments were conducted to see how effective the mitigating scheme is, as the scheme acts as a proxy server to Session Initiation Protocol (SIP) server. The experiments show that; when the VoIP server is under coordinated call attack without a mitigating scheme only 15.2% of legitimate VoIP users had access to the VoIP network and out of which about half of the legitimate users had their calls dropped before completion, while with the 2-tier mitigating scheme, when the VoIP server is under coordinated call attacks over 90.3% legitimate VoIP callers had their calls through to completio

Extent of Extension Service Delivery for Agro-pastoralists in Niger State,Nigeria

The study examines the extent of agricultural extension services deleivery to agro-pastoralists in Niger State. Nigeria. Primary data were collected through field survey from agropastorialist from three purposely selected Local Government Areas in Niger State. Katcha, Paiko and Wushishi LGA’s were purposely selected by making sure they were in different agricultural zones of the Niger State namely Zone I, II and III respectively. Twenty percent of the agropastoralists house-hold population was sampled from each of three LGA randomly. A total of 210 household heads were sampled and interviewed using a semi structured survey instrument administered by trained enumerators who understood the local language. Both descriptive and inferential statistics were employed to analyse the data. Results revealed that all (100%) of the household heads were all males and 67.7% acquired adult education while agro-pastoralism was the major occupation (98.1%). Majority (98.1%) of the agro-pastoralists claimed they were of Fulani ethnic group. Information on out break of diseases (mean=3.9); provision of grazing reserves (mean=3.7) were reported high. Majority (99.5%) of the respondents opined that lack of easy access to vaccines and non- proximity of veterinary clinic were major constraints. In the testing of hypotheses, Pearson Product Moment Correlation (PPMC) showed a significant positive relationship between extent of extension service provision and the following variables namely Age (r =0.172; p<0.05), number of wives (r =0.163; p<0.05), number of children (r =0.222 and; p<0.05), and number of cows owned (r =0.221; p<0.05).  The result of Chi-square analysis shows that there was a significant relationship between Extent of extension provision and the settlement type (X2 =10.21; p<0.05), Extent of extension provision and educational level (X2 =12.20;p<0.05). It was recommended that government should make adequate arrangement for provision of neccessary infra-structure in the already gazzeted grazing reserve most especially vetinery clinics and make vaccine available and affordable for them. There is need to produce more radio programmes and also encourage formation of radio listening group since is one of the major source of information to their production system. Keywords: Agriculture, Extension service delivery, agropastoralist