Common protocol for distributed network file system

Common p o ocol o dis ibu ed ne wo k ile sysy em 231 COMMON PROTOCOL FOR DISTRIBUTED NETWORK FILE SYSTEM P. Peniak 1) , F., Kallay 2) 1), IT se ice cen e o Eas e Eu ope (SCEE) Con inen al AG, Con inen al Ma ado T uck Ti es s. .o T.Vanso ej 1054/45, 020 01 Púcho , el.: +421 42 4613479,e- mail: pe e .peniak@con i.sk 2), Facul y o Elec ical Enginee ing, Uni e si y o Žilina, Uni e zi ná 8251/1, 010 26 Žilina, e- mail: edo .[email p o ec ed]za.sk Summa y Pape deals wi h common p o ocol o dis ibu ed ne wo k ile sys em. Focus is on CIFS p o ocol om Mic oso , he enhanced e sion o Mic oso Se e Message Block (SMB), ha is p oposed as possible common solu ion o ile sha ing among dis ibu ed sys ems. The e a e new equi emen s included as well, ha a e o be implemen ed due o ecen changes in applica ions and de ices and has been add essed in new gene a ion o dis ibu ed ile sys em p o ocols such as AFS2, CODA and WebDAV. 1. INTRODUCTION A ne wo k ile sys em is de ined as any compu e ile sys em ha suppo s sha ing o iles, p in e s o e a compu e ne wo k. Ne wo k ile se ices enable compu e s a ached o he ne wo k o access iles s o ed on o he compu e s in he same way ha hey access iles on hei own disks. Tha is, he clien in e ace used by p og ams should no dis inguish be ween local and emo e iles. I is up o he ne wo k ile sys em o loca e he iles and o a ange o he anspo o he da a [1], [2]. The compu e which p o ides access o i s iles and di ec o ies is called ile se e , and he compu e using hese iles and di ec o ies is he clien . A compu e can be clien and se e a he same ime. Fo communica ion be ween se e s and clien s, he speci ic ne wo k p o ocols a e used. The mos popula a e he ollowing p o ocols, see Tab.1: Tab.1 Ne wo k ile sys em p o ocols – No ell Ne Wa e DoD TCP/IP Mic oso Ne wo k 7 6 NCP FTP, HTTP, NFS SMB, RPC 5 Ne BIOS 4 SPX TCP/UDP 3 IPX IP Ne BEUI  NFS(Ne wo k File Sys em) –SunSys ems, IETF  NCP (Ne Wa e Co e P o ocol) -No ell  Se e Message Block (SMB) –IBM, Mic oso  File T ans e P o ocol (FTP) -IETF  Hype ex T ans e P o ocol (HTTP) -IETF These p o ocols we e implemen ed in he di e en ope a ion sys ems such as Mic oso Windows (SMB) and UNIX/LINUX (NFS) [3]. The e o e, hei clien s canno use he di e en ne wo k ilese e s by de aul , as shown in Fig.1a). The e a e mul i-clien solu ions applied, wi h se e al implemen ed ne wo k ile sys em p o ocols wi hin gi en ope a ion sys em. Fig.1b) shows mul iclien con igu a ion, wi h he p o ocol s acks o NFS and SMB (SAMBA implemen a ion o SMB se e in LINUX) so use s who wo k wi h UNIX o Mic oso ope a ion sys ems, a e able o use he bo h ne wo k ile sys ems. Ano he op ion is o de elop and implemen a common ne wo k ile sys em ha would be suppo ed by all pla o ms and supplie s. Then, jus one p o ocol s ack could be used o access and sha ing iles ia In e na . This op ion is shown in Fig.1c. a) b) c) Fig.1 Possible access o ne wo k ile sys ems 232 Ad ances in Elec ical and Elec onic Enginee ing Due o Mic oso supe io i y in numbe o ins alled nodes in In e ne , he in oduc ion o common ne wo k ile sys em p o ocol will equi e i s s ong suppo and accep ance. Mic oso is cu en ly ying o es ablish i s p o ocols as he o icial s anda d o he In e ne . I could pe spec i e eplace he cu en ly used FTP p o ocols and ile ans e s h ough he HTTP p o ocol, which ep esen s subs an ially he e ogeneous en i onmen wi h p oblema ic secu i y. Mic oso has been ying o push Common In e ne File Sys em (CIFS), p o ocol h ough s anda diza ion p ocess since 1996 [4]. CIFS d a s we e e en p o ided o IETF so ha i could be app o ed among In e ne s ada d p o ocols. 2. COMMON INTERNET FILE SYSTEMS Common In e ne File Sys ems (CIFS) is he enhanced e sion o Mic oso Se e Message Block (SMB) p o ocol ha de ines a emo e ile- access o sha e da a on local disks and ne wo k ile se e s, among dis ibu ed sys ems ac oss in ane s and he In e ne . In addi ion o SMB, which was de eloped on he op o NETBIOS-API, CIFS is able o un o e TCP/IP and u ilizes he Domain Naming Se ice (DNS). I is op imized o suppo communica ion ia In e ne wi h a ious speed le els. CIFS complemen s Hype ex T ans e P o ocol (HTTP) while p o iding mo e sophis ica ed ile sha ing han adi ional p o ocols, such as FTP. The CIFS p o ocol is no only a ailable o se e s and PCs, bu also o embedded de ices and dis ibu ed sys ems. I had o be scaled down in size and ewo ked o mul i asking ea u es o mee he needs o embedded de ices such as eal- ime, de e minis ic esponse imes, small memo y, and a a ie y o mic op ocesso – ile sys em combina ions. The using o CIFS o se e s and embedded de ices is shown in Fig.2. The ile sha ing is independen on hos ing pla o m and embedded ope a ion sys em/ ile sys em. Fig. 2 CIFS p o ocol in se e s and embedded de ices CIFS p o ides he ollowing unc ions:  File Access  Suppo o basic ile ope a ions (open, close, ead, w i e and seek).  Reco d lock and unlocking o mul iple clien s access and ile sha ing and locking.  Pe o mance and po abili y  Highly in eg a ed wi hin he ope a ing sys em.  Suppo o all ecen Mic oso pla o ms and o he ope a ion sys ems such as Unix, VMS, IBM, Macin osh  Secu i y  Suppo o anonymous access(no au ho iza ion).  Enhanced secu i y and au hen ica ed access  Op imiza ion  Imp o ed p o ocol pe o mance  Reduc ion o o e head in SMB p o ocol  Global File Names  No need o moun emo e ile sys ems,  Access based on globally signi ican names  Unicode File Names Because CIFS is mainly based on SMB p o ocol we will explain below i s co e unc ions. 3. SMB PROTOCOL The SMB (Se e Message Block) p o ocol was o iginally de eloped by he company IBM in co-ope a ion wi h he company Mic oso o one o he i s ne wo k ope a ing sys ems, he PC Ne wo k P og am .1.0. Today, his p o ocol is he mos equen ly used one in he ield o pee - o-pee communica ion o LAN ne wo k ile se e s and clien s. The SMB p o ocol is cu en ly used by ile and p in se e s IBM, Mic oso ’s ne wo k ope a ing sys ems (Lan Manage , Windows NT, XP, Vis a). The p o ocol heade and basic se ices a e shown in Tab. 2 and Tab. 3. Tab. 2 Heade o SMB p o ocol SI D S C R C A H RC RS NI D PI D UID MI D P PC d BL B 1 3 1 1 1 2 15 2 2 2 2 1 2 2 1 Σ 38 B MARKING MEANING SID SMB Iden i ica io n Iden i ica ion o SMB p o ocol (0xFF) S Se e Iden i ica ion o SMB se e ’s dialec C Command Func ional code o called SMB se ice R Re u n Class SMB unc ion e u n code class AH P ocesso AH egis e Resul o ope a ion in egis e o AH p ocesso RC Re u n Code Re u n code o ope a ion RS Rese e Rese e o u u e ex ension NID Ne Pa h ID Iden i ie alloca ed o sha ed means PID P ocess ID Iden i ie o clien ’s p ocess UID Use ID Iden i ie o use MID Mul iplex ID Mul iplex iden i ie o clien p ocess P mc Pa ame e Coun Numbe o op ional pa ame e s o called unc ion Common p o ocol o dis ibu ed ne wo k ile sysy em 233 PC Pa ame e Code Called unc ion pa ame e code BL Bu e Leng h Leng h o da a pa o SMB block B Bu e Fi s oc e o da a pa o SMB block Tab.3 Example o SMB se ices The SMB block wi h a clien ’s eques and a se e ’s answe a e p ac ically iden ical, hey jus di e in he da a pa and he leng h o he da a bu e . An example o communica ion o a clien wi h an SMB se e can be seen in Fig. 3. Fig.3 Example o clien communica ion wi h SMB se e The p o ocol wo ks on he basis o he clien /se e model. A se e p o ides o ne wo k clien s he co- called sha ed esou ces, usually sha ed disks, di ec o ies, p in iles and named pipes. Sha ed esou ces a e iden i ied h ough an uni e sal ne wo k add ess called UNC se e _name esou ce_name. A clien secu es he o mula ion o equi emen s o sha ed se e esou ces. The SMB se e analyses equi emen s sen by a clien in he o m o an SMB block (packe ), i checks an access pe mission, and based on ha i ca ies ou a equi ed ope a ion ( ile opening, w i ing in o p in ile, c ea ion o a di ec o y, e c.) The eply, oge he wi h he esul , is sen o he clien in an iden ical SMB block. In he implemen a ion o SMB se e s, wo di e en me hods o secu ing access o sha ed means o he se e a e o e ed h ough:  con ol o access a he sha e le el  con ol o access a he use le el In he i s case he access o sha ed esou ces is allowed o all ne wo k nodes ha ha e a alid passwo d alloca ed o a esou ce o a se e . Du ing an a emp o access any se e esou ce, a passwo d is equi ed om he clien . A e i s success ul en e ing, an NID (Ne wo k ID) esou ce iden i ie is alloca ed o he clien , h ough which i accesses he esou ce. Thus a numbe o passwo ds wi h di e en access le els can be alloca ed o each sha ed se e esou ce. In he o he case, he clien is e i ied hough a name and a passwo d immedia ely a e he connec ion o he se e , and in he e en o hei co ec ness, he se e alloca es o he clien i s use iden i ie UID (Use ID), h ough which he se e de i es access igh s o indi idual sha ed esou ces. In a mul i-use en i onmen , when se e al p ocesses can communica e simul aneously wi h he se e , a couple o PID (P ocess ID) and MID (Mul iple ID) iden i ie s can se e o hei dis inguishing. The clien sends he se e an SMB_COM_NEGOTIATE eques , h ough which he se e and he clien nego ia e connec ion pa ame e s and a suppo ed p o ocol e sion. Subsequen ly, he clien sends o he se e a SMB_COM_SETUP eques , in which he e is he use ’s name and passwo d. I he se e wo ks in he use -le el mode, i alloca es an UID iden i ie o he clien . Th ough he SMB_TREE_CONNECT message he clien connec s o a sha ed di ec o y wi h a TID iden i ie alloca ed by he se e . Then he c ea ion o a ( x) FID subdi ec o y and he disconnec ion o he se e ollows. SMB BLOCK CODE SERVICE SMB_COM_CREATE_DIRECTORY 0x00 C ea ion o di ec o y SMB_COM_DELETE_DIRECTORY 0x01 Dele ion o di ec o y SMB_COM_OPEN 0x02 Opening o ile SMB_COM_CREATE 0x03 C ea ion o di ec o y SMB_COM_CLOSE 0x04 Closing opened ile SMB_COM_DELETE 0x06 Dele ion o ile SMB_COM_RENAME 0x07 Renaming o ile SMB_COM_READ 0x0A Reading om an opened ile SMB_COM_WRITE 0x0B W i ing in o opened ile SMB_COM_LOCK_BYTE_RANGE 0x0C Locking ile by e ange SMB_COM_UNLOCK_BYTE_RANGE 0x0D Unlocking ile by e ange SMB_COM_CHECK_DIRECTORY 0x10 Sea ching h ough di ec o y SMB_COM_SEEK 0x12 T ans e in open ile SMB_COM_TREE_CONNECT 0x70 Connec ion o sha ed means SMB_COM_TREE_DISCONNECT 0x71 Disconnec ion om sha ed means SMB_COM_NEGOTIATE 0x72 Nego ia ion o SMB pa ame e s SMB_COM_SESSION_SETUP_ANDX 0x73 Connec ion o SMB se e SMB_COM_LOGOFF_ANDX 0x74 Disconnec ion om SMB se e SMB_COM_OPEN_PRINT_FILE 0xC0 Opening p in ile SMB_COM_WRITE_PRINT_FILE 0xC1 W i ing o p in ile SMB_COM_CLOSE_PRINT_FILE 0xC2 Closing p in ile SMB_COM_NEGOTIATE NID:0,UID:0,PID:53 SMB se e SMB clien 139 1029 SMB_COM_SETUP NID:0,UID:1,PID:53 SMB_COM_TREE_CONNECT NID:10,UID:1,PID:53 SMB_COM_CREATE_DIRECTORY NID:10,UID:1,PID:53,FID:1 „ x“ SMB_COM_TREE_DISCONECT NID:100,UID:1,PID:53 SMB_COM_TREE_DISCONECT NID:0,UID:0,PID:53 234 Ad ances in Elec ical and Elec onic Enginee ing Fig.3: Example o SMB packe 4. CONCLUSION T adi ional ne wo k ile sys ems we e c ea ed in a wo ld whe e he dominan ne wo k pa adigm was he LAN/WAN. Lack o s anda diza ion caused ha common s anda d has no been selec ed and app o ed ye , despi e o ISO s anda d FTAM (File T ans e and Access P o ocol) and ecen Mic oso ac i i ies wi h i s p oposed solu ion -CIFS. In addi ion he ne wo k ile sys em challenge has become he dis ibu ed ile sys em and connec ions ia In e ne /WAN, as he e is mo e om sel - con ained LAN en i onmen s o a wo ld o dis ibu ed sys em and e en a ely connec ed de ices. This kind o ne wo k en i onmen in oduces a leas h ee main challenges:  Au hen ica ion  Da a T anspo  Synch oniza ion Some o hese issues could be sol ed a he applica ion le el a he han he ile sys em le el. Fo ins ance, Rsync, a powe ul p og am ha came ou o he Samba p ojec p o ides emo e ile synch oniza ion o e he ne wo k. Ano he al e na i e o adi ional p o ocol is o example, AFS (And ew File Sys em) and CODA. Coda is a dis ibu ed ile sys em de eloped om AFS2. Coda is designed o mobile compu ing in an occasionally connec ed en i onmen . Coda clien s main ain a pe sis en cache o copies o iles om he se e . Coda checks he ne wo k bo h o he a ailabili y o connec ions be ween clien and se e , and o he app oxima e bandwid h o he connec ion. As explained he e a e s ill he di e en solu ions in place, such as NFS in Unix and CIFS/SMB in Mic oso wo ld. The u u e de elopmen mus conside no only equi emen o common ile sys em and p o ocol, bu also o include he new equi emen s ega ding dis ibu ed sys ems, eplica ions, caching, which ha e no been aken in o conside a ion ye . The e o e he nex de elopmen will ha e o sol e he men ioned challanges and o come wi h a p oposal o new solu ion, which will enable implemen a ion o dis ibu ed ile sys em o open and embedded sys ems as well. REFERENCES [1] FRANEKOVÁ, M., KÁLLAY, F., PENIAK, P. VESTENICKÝ, P.: Komunikaná bezpenos p iemyselných sie í. ŽU Žilina, 2007, ISBN 978-80-8070-715-6. [2] KÁLLAY, F., PENIAK, P.: Poí ao é si  LAN/MAN/WAN a jejich aplikace, G ada, 2003, ISBN 80-247-0545-1. [3] PUŽMANOVÁ, R.: Mode ní komunikaní sí  os A do Z, Compu e p ess 2002, ISBN 80- 7226-098-7. [4] i m documen a ion