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PC 1

1. a ch IP (IP Address)Khi mot may tnh ket noi vao mang

(Internet) th a ch IP o la duy nhat. Tuynhien, a ch nay cha han la co nh.Neu ban ket noi mang thong qua ISP th soIP se thay oi cac lan ket noi.

2. S khac nhau gia hostname va a chIP

n gian ch la viec goi ten. V duwww.yourname.com se de hn nhieu oivi viec phai goi 202.32.156.14. Tuy vay, cos khac biet quan trong gia hai ieu nay,IP la so dung e xac nh thiet b (device)

con hostname la moi lien ket gia mot tkhoa va so IP. Mot a ch IP co the conhieu hostname khac nhau nhng mothostname th ch co mot IP lien ket vi no.

a ch IP gom 4 ch so, cach nhau bidau cham va co gii han t 0 - 255. Moi soc lu bi mot byte nen IP co kch thcla 4 byte, c chia thanh cac lp a ch

A, B va C. Neu lp A, ban co the co 16trieu a ch, lp B co 65536 a ch. Vdu: lp B co 132.25, chung ta co tat caa ch t 132.25.0.0 en 132.25.255.255.

Phan ln a ch lp A la s hu cua caccong ty hay cua to chc. Thong thng,nha cung cap dch vu ISP s hu mot vaia ch lp B hoac C. V du: Neu a ch IPcua ban la 132.25.23.24 th ban co the xacnh ISP cua ban la ai (co IP la 132.25.x.).

3. IP spoofing la g?Spoof IP co hieu qua la khi ban vt

qua Firewall, lay cap account va can dauthong tin ca nhan, khi dung chc nang nayth chung ta khong nhan c thong tinphan hoi chnh xac, v a ch IP a cgia mao sang mot a ch IP khac.

4. Cong ao la g? (Virtual Port)nh ngha cong ao: La mot so nguyen

c ong goi trong TCP (TranmissionControl Protocol) va UDP (User DiagramProtocol). ng vi moi chng trnh trong

Windows se dung mot cong rieng e

truyen va nhan d lieu. V du may co ach IP la 127.0.0.1 chay WebServer, FTPServer, POP3 server th nhng dch vunay eu c chay tren mot a ch IP la127.0.0.1. Khi mot goi tin c gi en, lamthe nao may tnh cua chung ta phan bietc goi tin nay i vao dch vu nao

WebServer hay FTP server hay SMTP? Vvay, khai niem Port xuat hien. Moi dch vuco mot Port mac nh, v du FTP co portmac nh la 21, web service co port macnh la 80, POP3 la 110, SMTP la 25. Ngoai

ra, ban co the thay oi Port mac nh bangPort mapping. ieu nay rat n gian ch laqua trnh chuyen oi so port mac nh cuamot dch vu nao o thanh mot port khac.

V du Port mac nh cua WebServer la 80nhng thnh thoang ban van thayhttp://www.xxx.com:8080/ , 8080 ay

CBANChng 1

CAC KHAI NIEM

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chnh la so port cua host xxx nhng ac ngi quan tr cua host nay chuyenoi (map) t 80 thanh 8080.

5. RFC la g?RFC viet tat cua Request For Comments,

la tap hp nhng tai lieu ve kien ngh, exuat va nhng li bnh luan lien quan trctiep hoac gian tiep en cong nghe, giaothc mang Internet. Cac tai lieu RFC cchnh sa, thay oi en khi tat ca cac kys thanh vien cua IETF (InternetEngineering Task Force) ong y va duyet,sau o nhng tai lieu nay c xuat ban vacong nhan la mot chuan giao thc choInternet. Tai lieu RFC noi tieng va tao ctieng vang ln nhat la tai lieu RFC so 822

ve Internet Email bi Dave Crocker.Trang chu cua RFC:

http://www.ietf.org/rfc.html

6. DNS la g?DNS viet tat cua Domain Name Server.

Mot may chu DNS ket noi port 53, congha la neu ban muon ket noi vao maychu nay, ban can phai ket noi thong quaport 53. May chu chay DNS phan giai host-name thanh cac ch so tng ng va ngclai. V du: 127.0.0.1 -> localhost va localhost

-> 127.0.0.1

7. Thi Gian Song (Time To Live)Nh ban a biet Internet la mot mang

rat rong ln. e am bao cac goi d lieuen c may ch th qua la mot van e.

V the khai niem "Time To Live" ra i.Trong trng hp nhng goi tin nay khongen c may ch sau khi a i qua motso router (so nay a c mac nh trc)th no se t phan huy.

Time To Live (TTL) la thi gian goi d

lieu ton tai tren mang trc khi no b boqua. Ngi gi d lieu i se xac nh motgia tr TTL trc, thng la t 32 -> 64. Giatr nay se c giam i khi c chuyenqua bo nh tuyen tren mang (router). Khi

gia tr nay bang 0, datagram nay b bo quava giao thc ICMP (Internet ControlMessage Protocol) se bao loi ve cho ngigi. ieu nay se tranh cho datagram nay i

vao mot vong lap vo tan qua cac bo nhtuyen.

Moi bo nh tuyen khi nhan c IPdatagram se giam gia tr TTL cua datagramnay i mot. Hau het cac bo nh tuyen eukhong gi lai datagram nay trong thi gianqua 1 giay trc khi chuyen datagram nayi. Nen gia tr TTL co the coi bang hop

(counter) = so bo nh tuyen ma datagramnay va vt qua.

Khi bo nh tuyen nhan c mot data-gram co trng TTL bang 0 hoac 1, no sekhong chuyen datagram nay i tiep. Thay

vao o, no se bo qua datagram nay va gimot ICMP message "Time Exceeded" (quathi gian) tr lai cho ngi a gi datagramnay! V ICMP message ma bo nh tuyengi tr lai cho ngi gi co a ch nguon- source address la a ch IP cua bo nhtuyen nen ngi gi co the biet c ach IP cua router nay.

8. Khai niem "Time Out""Time out" c dung e mieu ta

khoang thi gian may A gi mot goi tin chomay B nhng khong nhan c tra li tmay B. V du, khi ban ket noi vao mot serv-er chat nao o chang han nh Viet chat,ban nhap vao nut Connect nhng saukhoang mot phut vietchat server van chatra li. ay goi la time out.

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PC 3

I. CAC CONG CU HACK MAY TNH

1. Loai bo password Administrator bang Active Password Changer 3.01.1 Gii thieu

- Khi ban muon xam nhap vao mot may tnh nao o th luon gap mot so tr ngai nhcan phai ang nhap bang password BIOS, Password Administrator, hoac mot so passwordcua mot so phan mem bao mat khac. V ly do nay, toi xin gii thieu mot so cong cu nhamgiup ban khac phuc tr ngai nay.

- Vi Active Password Changer, ban hoan toan co the xam nhap vao may tnh mot cachde dang va hieu qua.

1.2 Hng dan s dung1 Khi ong may tnh bang a CD (a

Hirent 's Boot 8.0), man hnh Boot cuaa nh sau (xem hnh 1.1).

2 Dung phm mui ten e di chuyenthanh sang hoac dung cac so cuamenu Boot (cac so co gia tr nguyenbat au t 1). e thc hien, nhanphm so9 hoac di chuyen thanh sangen menu Next sau o nhan Enter(xem hnh 1.2).

3 Di chuyen thanh sang en menuPassword & Registry Tools nhan

Entere tiep tuc (xem hnh 1.3).4 Di chuyen thanh sang en menu

Active Password Changer 3.0(NT/2000/XP/2003), nhan Enter etiep tuc.

Ban i mot chut e chng trnh cgiai nen len RAM. Sau khi qua trnh

II THIEUCAC CONG CU HACK

Hnh 1.1: Man hnh Boot cua CD Hirent Boot CD 8.0

Hnh 1.2: Man hnh Boot tiep theo cua Hirent's BootCD

Chng 2

G

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giai nen hoan tat, giao dien cua chngtrnh nh hnh 1.4.

5 Chng trnh gom co 3 tuy chon sau:

+ Neu biet ro he ieu hanh c cai treno a nao th nhan so 1 (Choose LogicalDrive).

+ Neu ban khong biet ro he ieu hanhc cai tren o nao th ban nhan so 2(Search for MS SAM Databases on all hard

disks and Logical drives).+ Neu khong muon chay chng trnh nayna th nhan so3.

Trong v du nay, toi chon 1, nhan Enteretiep tuc.

6 Nhap vao Partition cha he ieu hanh(cac Partition c anh so t 0) (xemhnh 1.5). Nhan Entere tiep tuc.

Luc nay, chng trnh se tm trong o a

hien hanh tap tin SAM va liet ke danh sachcac Accounts hien co va thong ke thanhmot danh sach theo so th t bat au t 0(xem hnh 1.6).

7 Nhap vao Account muon loai boPassword bang cach nhan phm so, gias toi muon loai bo Password

Administrator, nhap so0. Sau o, nhanEntere tiep tuc.

8 anh dau chon muc Password NeverExpires (Password khong bao gi hethieu lc) va muc Clear this user'spassword (loai bo password accountnay) bang phm Spacebar (xem hnh1.7).

9 Nhan phmYe loai bo Password, lucnay xuat hien giao dien cua chngtrnh (xem hnh 1.8).

Hnh 1.3: Man hnh Password Tools

Hnh 1.4: Giao dien Active Password Changer 3.0

Hnh 1.6: Danh sach cac Accounts

Hnh 1.7: anh dau cac muc chon

Hnh 1.8: Qua trnh loai bo password

Hnh 1.5: Danh sach cac Partition

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PC 5

10 Nhan mot phm bat ky e tr ve menuchnh.

Sau khi a loai bo Password thanhcong, ban co the ang nhap vao may tnh

vi tai khoan Administrator ma khong can

Password. Sau khi a ang nhap c vaomay tnh cua ngi khac th ban co thehoan toan quyet nh moi tai nguyen hienco trong may tnh nay.

2. Loai bo Password BIOS

2.1 Gii thieuPassword BIOS la mot password c

lu trong Bios cua MainBoard. Co nhieucach e loai bo password nay. Cach coien la ban thao nap may tnh va thao Pin

BIOS hoac co the lien he vi nha san xuatphan cng e ho cung cap cho ban pass-

word mac nh cua BIOS. Cach ma toimuon gii thieu cung ban se n gian hnma khong can phai thao cac thiet b phancng.

Khi Password BIOS c cai at thtrc khi khi ong, he thong yeu caunhap password. Neu password ung thmi cho ang nhap ngc lai th khong.Password nhap sai qua 3 lan th may tnhse khi ong lai hoac treo may (xem hnh1.9).

2.2 Cach thc hien

*Loai bo Password BIOS bang Debug

1 Vao Start > Run, go cmd, nhanEnter.

2 Nhap vao oan ma sau:

Debug

o 70 2f

o 71 ff

q (nhan phm nay e thoat khoi Debug)(xem hnh 1.10).

* Loai bo password BIOS bang chngtrnh hp ng trong Debug

T dau nhac lenh cua man hnh DOS,nhap ch Debug, sau o nhap vao oanma sau:

Debug

-A

mov ax,0

mov ax,cx

out 70,al

mov ax,0

out 71,al

inc cx

tb 103

int 20

q (e thoat khoi debug).

3. Hng dan Crack Password

3.1 Gii thieuNh cac ban a biet e bao ve mot he

thong th viec bao mat password luon ccoi trong. V vay, phan nay se giup ban tmhieu mot chng trnh be khoa password.

Co rat nhieu cach e bao mat passwordtrong mot he thong. o la s ket hp gia3 yeu to:

- Something you know- Something you are

- Something you have

The nao la mot chng trnh be khoa(password cracker)? Va mot hacker oanpassword nh the nao?

Password cracker la mot chng trnh co

Hnh 1.9: Nhap Password BIOS

Hnh 1.10: Loai bo Password Bios bang ma Debug

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kha nang giai ma hoac vo hieu hoa pass-word. Hau het cac password cracker lamcong viec la xem xet cac bc ma hoapassword e pha v no (crack) hay dchngc no lai. Ky thuat nay se c mo ta

ky hn cac phan sau.Khong phai ngi nao cung quan tam

en viec la chon mot password an toan.Neu password co trong t ien th chacchan password o de dang b be gay(crack). Ch co nhng ngi a co kinhnghiem va rat can than mi quan tam enieu o. Tuy nhien, ho lai khong ng rangpassword nam trong mot th muc nao ohoac co nhng ngi khong can chon pass-

word phc tap bi v ho khong co tap tinquan trong. Tat ca ieu nay dan en he

thong b nguy hiem bi nhng hacker vanhng co may crack sieu hang.

Mot vai he thong cho phep ban otnhap vi nhng user nh "demo" hay"guest" ma khong can biet password, goi ladefault password. V sao co default pass-

word? ay la ly do:

Nhan vien cua mot c quan (hay thanhvien cua to chc) c phep quan ly motso tai nguyen nhat nh ma ngi chu(admin) cho phep bang cach dung default

password. Va trong trng hp admin lamot ngi ban ron vi cong viec, ho luonat password sao cho de nh("love","money",) hoac n gian pass-

word ch la mot khoang trang. Nhieu hack-er thng th cac default password, oanpassword trc khi ngh cac ke sach tinh vihn. Cac accounts cua user thng b hack-er tan cong trc e lay password va otnhap vao mot he thong vi user o. Ch khia an toan trong he thong, ngi tan congse tien hanh viec getadmin, anh cap file

cha password e giai ma... va... chac cacban cung oan c phai khong?

3.2 Password co c he thong bao ve tot

khong?au tien phai ke en cong cu tao pass-

word (password generator), no se giup ma

hoa password ban nhap vao. Hau het caccong cu nay s dung vai quy tac ma hoanao o. Cac ban co the tm c trenInternet mot trang web trnh bay rat chi tietcac cach ma hoa khac nhau. Trong muc

nay toi se ch neu len mot nh ngha ngangon va chung nhat cho tat ca cach ma hoa.

Ma hoa (Cryptography) c nhngha la "mot kieu viet ch ac biet datren khoa hoc va tr tue (the science andstudy of secret writing)" hay noi cach khac,o la cach d lieu c bao ve (encode)tranh khoi ban tay cua nhng ngi co ymuon xem trom hay pha phach...Co thedung ky t, ch so hay bat ky phng thcnao, sao cho ch co nhng ngi thc sbiet cach mi co the xem c noi dung

thc s cua no.Co hai loai he thong ma hoa:

- oi xng

- Khong oi xng

He thong ma hoa oi xng dung nhngt khoa giong nhau (t khoa ac biet) ema hoa cung nh giai ma mot thong iep(c xac nhan trong Windows).

He thong ma hoa khong oi xng sdung mot t khoa (t khoa chung, congkhai) e ma hoa va mot t khoa khac (t

khoa rieng, b mat) e giai ma. He thongnay con c goi vi mot cai ten khac la"He thong mat ma s dung t khoa chung(Public key cryptosytems) (PKC).

Chung ta lay mot v du ve thuat toanchuan ma hoa d lieu (Data EncryptionStandard DES) va xem no hoat ong nhthe nao. Password c lay t mot van ban

va s dung password ma nhieu ngi achuong: Password.

Password nay s dung mot t khoa e

ma hoa chuoi gia tr 0 (series of zeros) (64in all) va sau khi thc thi, gia tr nay sethay oi. Ket qua sau khi a chuyen sangmat ma c ghi vao mot van ban trong.Trong cuoc kiem tra cua chung toi tren hethong Win2000 ket qua cho ra8846F7EAEE8FB117AD06BDD830B7586C.