3.1. Gioi thieu
Nhu dA biet cac culic tAn cong co the duqc chia thitith hai loci la ben trong va ben ngoii. Trong khi cac cuOc tan ding ben ngoai duqc tier himh bed cac node khling thuOc 114 thong moc tieu MANET, the cuOc tan cong ben trong duqc thvc hien tir cac node th6a hip MANET. Nguqc Igi yen the cue‘c tan cong ben ngoii, the cuOc tan cong ben trong co anh Mien% nghiem tang ham veri hg Meng non nhan. Dieu nay lit do thvc to cac node ben trong (vi do: them hiep) co hieu biet lien quan den thong tin gia try' ve topo mang va cling co quyen truy c3p dAy
Tren ca ser ban chat dm sv tucmg tic tan Ong, cac cuec tan cong chang loi mpg MANET co the &Km phan thanh tan cong thu dOng va chit dOng. Tan cong chit dOng bao gam sao chop, chinh sire, ho3c looi 66 thong tin trao doi gifts cac node. Cac cuCic tan ding chit dOng chting 131 MANET co the dan den the nghen, truyen thong tin djnh tuyen kh8ng chinh xac, vi co the Ian cong tir eh& djch vti (DoS) kjch ban ma er d6 cac djch vu thr djnh bi ngfin can hoot dOng. Cfic cuOc tan ding chit dOng thubng duqc thvc hien bed cac node them hip (node dec hop hoc cac node co 13p (selfish) no chi drop cac goi tin nhen de tiet kiem nAng hrcmg. Holt dOng binh thuimg cua mong MANET bj gian dorm beri cac node co letp vi chimg khong tham gia vim cac giao thirc dinh tuyen va chuyen tiep the goi. M3t khac, met node them hip co the lqi dung giao thirc dinh tuyen quilt% bit ban than no co throng thin ngin that den Bich. Cac node co 13p (vd tan cong thu dOng) bao gam nghe trOm thong tin, phan tich luu lucmg, va giam sat luu lucmg de xay thing cac ha sa thong ke tir do coy ttremg ve de hoot dOng mong va c6 the a bj
Mn thuong cua MANET. Ck cuOc'tan cong thy ding kh6 phat hien va del ph6 hon.
Met cuec tan cong chit ding phO bien 11 gii moo theo do met node thea hip gia ver la met host hqp le. Node them hip thuimg lqi ding sy thiau xfic thyc trong cac giao thirc MANET hien tgi. Ket qui elm cic cuec tan cong gia moo la cac node khic trong mpg MANET c6 met hinh inh sal ve topo mpg vi trai qua cac yang 10p hoc phan vimg mpg. That voy, sy thieu xic thyc trong cac giao thirc djnh tuyen thong qua MANET cling din den the cuec tan cong lam gia no tao ra the tin
djnh tuyen sai.
Cac cuec tan cong DoS, c6 rat nhiau bien the va lira dao van la mat trong nhcmg logi phO bien nhat, nhtmg vin hieu qua, de dos chOng lai MANET vi the mang adhoc khac. Trong met cuec tan cong DoS thong thubng, ke tan cong due met khan Itryng lern cite gei tin kheing can thief vio trong mpg de tieu hao met Itrong lam tai nguyen mpg. Ket qua lit, cac node hqp le quilt tranh yeti nhau va cac kit not vi kenh truyen. C8ng viec trong xac dinh hai bien the curt tan cong DoS chang lgi MANET, cy the lit Sleep Deprivation (mat ngit) va tan cong tran bang djnh tuyen, no co ging litm can ki'et nguen nang luqng cos cac node myc tieu vi tao ra cic tuyen den cac node khong tan tai. Cac cuec Mn cong djnh tuyen phtic tap hon vao MANET nhu wormhole, Mn cong pito thity (Sybil), vi the cuec'tan cong don dap (rushing) kh6 phit hien hon de ngan chin met mirth. Can Itru y tin cac cuec tan cong nay dien ra tren lop mpg. Tren lerp van chuyen cling vay, mpg MANET de bj Mn thuong beri cic cuec tin Ong nhu chiem door phien (session hijacking) vi ngap lyt thing bij h6a (synchronize flooding). Ngoai ra, cac cuec tan cong chOng lai MANET co the xay ra ey cac lap thap hon. Vi du: phat tich Lim luqng vi giam sat (tan cong the ding) gay glint dogn chukt IEEE 802.11 a MAC, vi tuong ty co the cheng lai MANET dya tren cac host 6 tan lien kit dit lieu. 6 lap vat ly, gay nhieu (jamming) vi cac de Oa the ding khic nhu ch#n cic tin vi nghe trim la c6 Mn tai. Tuy nhien chuong nay se tap tnmg vao cic cuec tan cong bito mat khic nhau cheng Igi MANET tren lop mang va lap giao van.
3.2. Cic cu0c tin cong Itrp mong cluing Ini MANET
Cac giao thirc lop mpg cho phep cac node MANET duqc kit nail ved nhau thong qua buerc tai bare. Bin chit ty nhien coa cic giao thirc djnh tuyen MANET, do do, dim bio lien kit hop tic gicra cac node bang rich cho phdp chung hoot
Phan Trung Nghia A08348 &Ong nhu cac router hok cac thiet bi trung gian tren cong met duong an lien ket cilia met node nguon/nan nhan "V" va met node dich "D".
Hinh 3.1: Ca chi So mot cuoc tan cong dinh tuyin dun gicin
Cac kieu khic nhau cua cac cuec ten eking chang lai cac giao thirc djnh tuyen MANET dime xac djnh thong qua do met node dec hai "M" co the thu but Km
luting mpg vi dat no vim giva "V" va "D". "M" sau d6 co the kiem sok hieu qui
Kiang luu luting mang tit "V" an "D" (cling nhu cac throng khic xung quanh) nhu met router. "M" cling c6 the chuyen cac gai tin glib "V" vi "D" qua met dut:mg Ich8ng tOi uu hooc yang lap. Dieu nay lam tre dang ke kat not dau alai gala "V" va "D". Trong met kich ban ?tau han, "M" co the dieu khien cac gel qua met lien ket khong ton tai. Do de, cac cuec tan cling chang lai cac giao thirc mang lap mang tao ra met loaf cac van de nhu cac node MANET khong the tim thay bat kj, tuyen nito den dich, t e nghen
Ngoai ra, met so cuec tan cong nhAm den cac giao thirc dinh tuyen cq the. Vi dg: neu ca the dinh tuyen ca s6 nhu a hinh tren la DSR, sau do "m" co the chinh sira tuyen ngu6n duqc liet ke trong gai RREQ va/hoac cac g6i RREP, vi du: bang cach them met node men vito tuyen, x6a met node dang tan tai trong tuyen, thay ai thin fix cac node vi Wang ttr. mot khac, neu giao thtic AODV duce sir dpng, no co the xay ra nhu sau "M" quing do met tuyen yeti met chi phi (metric) khoing cach lam giti de no nho han so voi met tuyen that. Dieu nay lam cho viec cap nhat cac tuyen tir cac node khac kh8ng hqp le. N6 cling nhan manh rang "M" khong nhat thiet phiti thqc hien cac cuec tan cong b duy nhat giai down chuyen tiep du
lieu. Thtrc te, "M" co the thqc hien cac cuec ten cong dinh tuyen trtroc khi duOng dart dinh tuyen dirge xfic djnh, do la, trong suck qui trinh khan pha tuyen hooc duy
tri tuyen. Clic cuOc Uhl ding khic nhau duqc mo to trong phan con Igi cit.% chucmg
nay.
(vac cucic tan cong er qua trinh kham pha tuyin MANE?': flied s6 ngtriri dimg doe hal ttir Y 'thong tufin theo cac thong se ky thuot cita cac giao thin djnh tuyen sir dung trong mang MANET. Citc cuOc tan ding nay thtrimg dien ra trong suet qua trinh khfirn phi% tuyen. Vi du ve cac kieu tan cong nay bao gem ng3p lot tin djnh
tuyen (vi do: bang each trao din met luong coc Ion cac tin Hello, RREQ, va/hok ACK), tin ngiip bfing djnh tuyen, dau dee be dem djnh tuyen, va tan cong yang
lep djnh tuyen. Thvc te, the thuot toim dinh tuyen chit dOng (vi du: DSDV va OLSR) de khfim phi cac tuyen trong MANET lit a bj kieu tan cong nay ham so veri cac giao thirc phin ting nhu DSR vi AODV. LS, do lit djnh tuyen chu Ong ne
lye de kham phi th8ng tin dinh tuyen an thiet theo chu IcY va truerc khi thong tin djnh tuyen duqc you au. Vi du: met node dee hgi co the lam tran bang djnh tuyen cim met node nan nhfin bang each truyen quit nhieu cac tin quing cito tuyen. De ket thee, ngueri sir dung dee hgi quing hi tat ca cac tuyen trong tat ca cac topo MANET mire tieu. Ved dieu kien "M " thimh cong trong vile to ra du cac tuyen khong phe bien (nonprevailing), met thuit toitn chit dOng co the bj lira nhu khong too ra cac tuyen be sung. Cie giao thirc djnh tuyen chit Ong de bj Mn thircmg beri cac cuOc tan cong dAu dOc be dem (firth tuyen cong theo do "M" lqi dung the de
nem nhien trong qufi trinh c#p nhot cite bfing dinh tuyen cua the node trong MANET. tatting hop nay, "M" "du dOc" the tuyen den node non nhfin "V" bang each quing bit cac g6i giit moo vOi tuyen nguen den "V" qua chinh "M". Ket qui la cite node Ian con thong bfio cac gen co the them tuyen nay den be dem tuyen tucmg img cua chimg.
Cac cuac tan ding er qua trinh duy tri djnh hryin MANET: trong giai dogn duy tri tuyen, met se tin dieu khien duqc trao den gifts cac node tham gia vao topo
mang MANET. Met se cuOc tin cong duqc thvc hien trong giai dogn nay no
quitng bit cac tin dieu khien hoc tin hien gifi (vd: cac tin lei lien ket hong) de tien
hanh eau hinh lai ho#c citi dOt 13i tuyen to nguOn den dich. Vi do: de' gifii quyet sir
di dOng elm cac node trong MANET, the giao thirc dinh tuyen nhu AODV va DSR co ca the phttc hei cac tuyen bi hong. Trong the co the nhu v3y, khi the node dich va/ho#c the node khitc tren &rang din tit nguen den dich di chuyen, node nguqc clang (upstream) "U" cim lien ket bj hong phfit di met tin lei tuyen den mei node ngtrqc dong khic. Ngoai ra, "U" cong lam such tuyen d#c biet nay den dich. MOt ngutri dung dec hai, "M", co the lqi dung vai tro cim "U" qufing bit
Phan Trung Nghia A08348 sai cac tin lei tuyen va ngiin chen node nguem (node nan nhan trong twang hgp nay) tir lien ket vei dich.
Tan cong o giai dogn chuyin tiep citi lieu: rid nhieu cac cuec ten cong cheng
lai giao thee djnh tuyen MANET lqi dung chirc nang chuyen trap thong tin cim cac node MANET or lap mang. NhOng ke ten cong trong trtrimg hgp nay IchOng lam gian doan qua trinh khiun pha tuyen vaiho(tc duy tri. Thay vio d6 chfing san sang phi v0 the gOl dit lieu chuyen tiep theo thong tin bang djnh tuyen beri mot s6 phtrcmg tien. Vi du: met ngtreci dung dOc hai co the am them drop hoac phat lai hoec them chi chinh sira not dung gel di ye. Ngoiti ra, cac lien kat nhay cam than gian c6 the bj gian doan ben each lam tre viec chuyen tiep cac gei du lieu den cac dich tiep theo ttrcmg img hoec don giim lit dua vito ve chuyen tiep cac gel gia.
3.2.1. Tin cong Wormhole
Ten cong wormhole la met trong nhang de dqa phirc tap va nghiem trong &let dei vei djnh tuyen MANET, bao gem mot 4p nhung ke ten cong. Hai ke tat' cong thong deng de ghi lai cac g6i o met vi tri rieng trong topo mang va xem lai b melt node Ichic bang each sir dung met mang rieng ofic do cao.
RREQ4— IREP4—
lien kgt wormhole t6c do cao
Hinh 3.2: Kjch ban mot cuoc tan cong wormhole
Hinh tren cho they met kjch ban vi du ve cuec ten cong nay, trong de "Ml" va "M2" le nhi-mg ke ten cling thong deng va "V" la node nan nhan. Kb "V" quang ba mot tin RREQ de tim molt tuyen den node "D" (vi MA: "V" va "D" la cac node nguan ve dich), ngay lap tirc the node ling gieng cite "V", ci s' the la "A" va "F"
chuy'an tiep tin RREQ den Wing gieng Wong **mg ciut chting la "B" vi "Ml". Tuy nhien, "Ml" nh#n duqc tin RREQ tir "F", no chuyin tin RREQ qua met dtrOng hiun den ceng tac dm no "M2". Sau do quang ba tin RREQ den ling gieng Goa no la node "G", thong qua do tin RREQ duqc giri den node dich "D". Do cac lien kat Mc de cao duqc chon beri throng ham giva "Ml" vi "M2", can thin gian ngin han cho tuyen d4c biet nay de giri tin RREQ den "D" tucmg phan yen thin gian thtrc hien or throng dan {V-A-B-C-D-E}. Kat qua lit tuyen {D-G-F-V} trec thanh bra chcon it ring cho "D" de phat met tin RREP nhu mot phan hai den "V". Vi 4y, "D" b6 qua tin RREQ tuang to den sau do do tuyen hqp phap {V-A-B-C-E-D} mat hien lye. Dieu nay buec "V" lua chqn tuyen {V-F-G-D} ma tren thuc to la di qua "Ml" va "M2" la nhang ngu&i dung dec hai co the gia mgo cac gal dit lieu.