Skype lieu co an toan?

Co rat nhieu thong tin (trong do co khong it thong tin thieu chinh xac) ve muc do nguy hiem cua Skype doi voi mang doanh nghiep va nguoi dung ca nhan. Vay thuc su no nguy hiem nhu the nao? Trong bai nay chung ta se cung tim hieu.

Hieu ve cau truc co ban cua Skype

Skype la mot ung dung ngang hang (P2P), tuc la nguoi dung co the ket noi truc tiep voi nhau ma khong phai thong qua mot may chu trung tam. Ban dau Skype su dung cac server dua tren nen tang Internet de tham dinh nguoi dung khi dang nhap va theo doi trang thai cua ho. Nhung khi hinh thuc “chat” hay chuong trinh tin nhan tuc thoi (Instant Message), cac cuoc thoai may tinh (voice call) va truyen tai file ra doi, hinh thuc lien lac duoc chuyen sang ket noi truc tiep P2P. Neu mot hoac ca hai nguoi dung nam phia sau tuong lua thong dich dia chi mang doanh nghiep (Network Address Translation hay con goi la NAT Firewall), lien lac co the duoc tiep song qua mot “Sieu nut” (Supernode). Vi ket noi P2P truc tiep khong the duoc thiet lap sau tuong lua NAT. Trong truong hop truyen tai file, ban se thay co mot thong bao duoc dua ra noi rang qua trinh truyen tai dang duoc tiep song.

Mot trong nhung moi quan tam hang dau cua cac chuyen gia bao mat ve Skype la mot Skype client co the tim ra duong den quanh cau hinh tuong lua tong hop an toan qua de dang. Skype su dung cac cong 80 va 443, co trong hau het cac tuong lua de mo cho cac duong dan Web. Hon nua, Skype con co the dinh tuyen lai luu luong neu cong khoi tao duoc gan trong qua trinh cai dat Skype khong dung duoc. Dieu do gay kho khan rat nhieu cho viec loai bo Skype o muc tuong lua, vi cac cong Skype su dung co the thay doi neu can.

Skype cung ma hoa tung lien lac voi khoa AES 25-bit, tuc la moi lien lac se co mot khoa khac nhau trong tung thoi diem ban thuc hien, khien viec nghe trom cac lien lac hau nhu khong the thuc hien duoc.

Mot trong nhung diem dang luu y ve bao mat Skype la cac “Sieu nut” cua no (Supernote), co chuc nang dinh tuyen luu luong Skype. Mot Sieu nut la mot may tinh voi cau hinh rieng, ket noi truc tiep voi Internet va khong duoc nam sau tuong lua NAT. Chung phai co mot dia chi IP co the dinh tuyen chung “thuc”. Ngoai mot so gioi han do, sieu nut co the la bat ky may tinh cua nguoi dung Skype nao dap ung duoc yeu cau toi thieu ve phan cung va cau hinh.

Co rat nhieu thu ban co the hoc duoc ve cau truc bao mat cua Skype. Xem chi tiet tren website: Skype Security Resource Center.

Skype FUD

Ban da hieu duoc so so cach hoat dong cua Skype, bay gio chung ta se xem lieu no co nguy hiem khong va nguy hiem nhu the nao. Co rat nhieu khai niem sai lam ve Skype van dang troi noi tren the gioi mang. Duoi day la 5 khai niem sai pho bien nhat:

+ Skype su dung rat nhieu bang thong tren mot mang.
+ Bat ky may tinh nao cung co the la mot Sieu nut.
+ Skype giong nhu bat ky chuong trinh ung dung IM nao va de bi ton thuong boi cac sau, virus IM.
+ Skype kho co the go bo tren mang.
+ Skype duoc ma hoa, khong the truy van duoc cac tin nhan IM.

Chung ta hay xem thuc hu ve nhung van de nay ra sao.

Van de thu nhat: Skype su dung rat nhieu bang thong tren mang

Thuc te Skype su dung rat it bang thong, chi xap xi 30Kbit/giay cho mot cuoc thoai. Neu mot may tinh cua nguoi dung tro thanh Sieu nut thi tat nhien no se tieu thu muc bang thong cuc ky lon. Nhung nen nho rang, may tinh cua ban phai duoc ket noi truc tiep voi Internet thi moi tro thanh Sieu nut duoc. Con hau het cac may tinh trong doanh nghiep hay may tinh ca nhan deu phai ket noi voi Internet thong qua cac server trung gian. Boi vay, van de nay thuc su khong dang lo ngai.

Van de thu hai: Bat ky may tinh nao cung co the tro thanh Sieu nut

Chung ta da biet rang mot may tinh phai co dia chi IP co the dinh tuyen va nam truc tiep tren mang Internet moi co the tro thanh Sieu nut.

Neu may tinh nam trong mot mang cong ty dien hinh, duoc bao ve boi mot tuong lua cung cap NAT, dung khung dia chi IP rieng 192.168.x.x hoac 10.x.x.x thi no khong the tro thanh Sieu nut. Cac tuong lua NAT va tham chi ca cac router gia dinh giup ngan chan rat nhieu may tinh tro thanh Sieu nut.

Van de thu ba: Skype de dang bi ton thuong boi cac sau va virus IM

Nam ngoai, theo thong ke cua Akaonix Systems cho toi dau thang 12 thi co 1.355 sau va virus tan cong cac IM client, nhung khong co loai nao trong so do tac dong len Skype. Mac du Skype nhan duoc hai canh bao bao mat trong nam 2006, bon cho nam 2005 va mot trong nam 2004, nhung chua co canh bao nao bien thanh lo hong bi khai thac.

Lo hong chinh cua cac ung dung tin nhan tuc thoi (IM) la chuc nang truyen tai file, co the bi loi dung, cho phep ai do gui file chua malware. Cac chuong trinh quet virus duoc cap nhat lien tuc, chay trong mo hinh “auto-protect” (tu dong bao ve) co the doi pho duoc voi hoat dong nay. Ngoai ra, nhieu ung dung con co cac tuy chon quet IM rieng. Neu ban co mot phan mem anti-virus duoc cap nhat ban moi nhat, chay trong mo hinh “auto-protect”, ban khong can phai lo lang gi nhieu ve sau hay virus. Hoac ban co the ngat bo chuc nang gui file cua Skype neu muon an tam hoan toan.

Van de thu 4: Skype kho co the go bo tren mang

Skype chi kho go bo neu ban khong biet no co tren mang cua minh hoac neu ban khong co chuong trinh quan ly cau hinh tot cho cac client. Co nhieu cach go bo Skype, tu cach su dung cac script (kich ban) dung phan mem quan ly mang den cach go bo truc tiep tai tang mang.

Van de thu 5: Skype duoc ma hoa, khong the truy van duoc cac tin nhan IM

Dieu nay khong thuc su la sai. Cac phien hoat dong cua Skype duoc ma hoa, vi the ban khong the dong goi hay truy van lien lac Skype. Dieu nay cung dung voi rat nhieu ung dung IM khac. Vi the Skype cung khong kem an toan hon bat ky chuong trinh tin nhan tuc thoi (IM) nao khac co su dung ma hoa.

Ket luan

Cho den bay gio, Skype chua gap phai mot so rac roi kho chiu ve virus, worm nhu cac ung dung IM khac. Chi co mot van de thuong hay duoc nhac den la mot so dau hieu canh bao truoc khi co lo hong duoc kham pha va bi khai thac. Bat ky ung dung nao cho phep truyen tai file, gui tin nhan tuc thoi hay thuc hien cac cuoc thoai may tinh ma khong the giam sat, luu tru hay ghi thong tin deu phai chiu mot muc nguy hiem nao do.

Tuy nhien, cau truc cua Skype kho bi be khoa hon so voi mot so chuong trinh ung dung IM mo tren Internet. Vi the co the noi no la an toan nhat trong so cac ung dung IM. Nhung cung co mot so chuong trinh ung dung khong phuc vu cho ket noi Internet nhu Jabber tham chi con an toan hon cho cac lien lac IM noi bo. Song, cho den nay, neu dat cau hoi lieu Skype co an toan hon MSN Messenger, Yahoo Messenger, AIM hay ICQ khong, thi cau tra loi la “Co”.

(Theo QTM/ComputerWorld)