dhcp server ubuntu
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MC LC
LI NI U ................................................................................................................. 2
CHNG 1: GII THIU V DHCP ........................................................................... 3
1.1. DHCP l g? .......................................................................................................... 3
1.2. ngha ca vic s dng DHCP. ......................................................................... 3
1.3. Mt s thut ng c dng trong DHCP. .......................................................... 4
1.4. C ch xin v cp pht IP Address cho DHCP Client ca DHCP Server. ........... 4
1.5. C ch t ng refrest li thi gian ng k (lease time). ................................... 6
1.6. u im ca DHCP .............................................................................................. 6
CHNG 2: TRIN KHAI DHCP SERVER TRN UBUNTU SERVER .................. 8
2.1. Chun b trc khi tin hnh trin khai ................................................................ 8
2.2. Trin khai cu hnh ............................................................................................... 8
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Nghin cu trin khai DHCP Server trn Ubuntu Server
LI NI U
Ngy nay, cng ngh thng tin tr nn ph bin v m bo tnh hiu qu cho
hot ng sn xut, kinh doanh ca cc doanh nghip. i lin vi l s i hi v
kh nng p ng v cng ngh thng tin ni chung v s thng sut ca h tng mng
ni ring.
S pht trin ca Internet cng ng ngha vi vic tng trng v quy m v
cng ngh nhiu mng LAN, WAN, Chnh iu lm cho vn s dng vi
tnh cng tng v vi quy m ln. Do , vn d qun l v cu hnh tr nn quan
trng hn bao gi ht. Vic thit k mng v cp pht a ch IP t ng sao cho nhanh
chng, tit kim thi gian v cng sc, ti nguyn ca t chc l vn ng quan
tm. Internet pht trin cng mnh, lng ngi truy cp cng tng, nhu cu s dng
vi tnh cng nhiu th ngi qun tr mng cng phi tn nhiu cng sc bo tr,
qun l, m rng kh khn hn.
Dynamic Host Configuration Protocol (DHCP) l giao thc cu hnh a ch IP
ng, l dch v trn nn giao thc TCP/IP nhm n gin ha vai tr qun tr ca vic
cu hnh a ch IP ca mng Client.
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Nghin cu trin khai DHCP Server trn Ubuntu Server
CHNG 1: GII THIU V DHCP
1.1. DHCP l g?
DHCP l vit tt ca Dynamic Host Configuration Protocol l giao thc cu
hnh a ch IP ng, l phn m rng ca BootProtocol, DHCP c nhim v l cp
pht a ch IP ng cho cc Client.
My tnh c cu hnh mt cch t ng v th vic s dng DHCP s gim
vic can thip vo h thng mng. N cung cp mt database trung tm theo di tt
c cc my tnh trong h thng mng. Mc ch quan trng nht l trnh trng hp
hai my tnh khc nhau li c cng a ch IP.
DHCP bn cht l mt dch v c s h tng c trn bt k mt h thng mng
no nhm cung cp a ch IP v thng tin DNS server ti cc PC client hay mt s
thit b khc.
1.2. ngha ca vic s dng DHCP.
DHCP c s dng gip bn khng phi n nh a ch IP tnh cho tt c
cc thit b c trong h thng mng ca mnh v gip bn qun l mi vn m a
ch IP tnh c th to ra.
Thng thng trong mt m hnh mng, ngi qun tr c th cu hnh IP cho
cc my client theo hai cch l th cng (static) v cp pht ng (dynamic). Vi cc
h thng mng nh static c th p ng c nhu cu y, nhng vi cc mng ln th
vic cp pht IP mt cch t ng l thit yu hn c v DHCP ra i p ng nhu cu
y.
DHCP cho php cc nh qun tr mng c th t mt trung tm qun l v t
ng m ha qu trnh gn IP cc thng s cho mt mng my tnh trong mt khong
thi gian nht nh.
Tt c vic trao i thng tin gia mt DHCP server v DHCP client s s dng
User Datagram Protocol (UDP) port l 67 v 68.
Ngoi vic cung cp a ch IP, DHCP cn cung cp thng tin cu hnh khc, c
th nh DNS. Hin nay DHCP c 2 version: cho IPv4 v IPv6.
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Nghin cu trin khai DHCP Server trn Ubuntu Server
1.3. Mt s thut ng c dng trong DHCP.
DHCP client My trm DHCP: l mt thit b ni vo mng v s dng giao
thc DHCP ly cc thng tin cu hnh nh l a ch mng, a ch my ch
DNS.
DHCP server My ch DHCP: l mt thit b ni vo mng c chc nng tr
v cc thng tin cn thit cho my trm DHCP khi c yu cu.
BOOTP relay agents Thit b chuyn tip BOOTP: l mt my trm hoc mt
router c kh nng chuyn cc thng ip DHCP gia DHCP server v DHCP
client.
Binding Ni kt: l mt tp hp cc thng tin cu hnh trong c t nht mt
a ch IP, c s dng bi mt DHCP client. Cc ni kt c qun l bi
my ch DHCP.
1.4. C ch xin v cp pht IP Address cho DHCP Client ca DHCP Server.
Giao thc DHCP lm vic theo m hnh client/server, do quy trnh cp pht
IP cho client c thc hin qua bn bc sau:
IP lease request
IP lease offer
IP lease selection
IP lease acknowledgement
1.4.1. IP Lease Request
u tin t DHCP client s broadcast mt message tn l DHCP discover. V
lc ny client cha c a ch IP nn n s c source l 0.0.0.0 v cng khng bit
c ch n l server no nn n s gi 1 tin broadcast ln ton mng. Gi tin ny
bao gm c a ch MAC DHCP server c th bit c client no gi yu cu
n.
1.4.2. IP Lease Offer
Nu c mt DHCP server nhn c gi tin DHCPDISCOVER ca client th
n s tr li li bng mt gi tin DHCPOFFER, gi tin ny i km theo nhng thng
tin sau:
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Nghin cu trin khai DHCP Server trn Ubuntu Server
MAC address ca client
IP address cp cho (offer IP address)
Mt subnet mask
Thi gian thu
a ch IP ca DHCP cp IP cho client ny
Lc ny DHCP server s c gi li mt IP offer (cp) cho client n
khng cp cho DHCP client no khc.
DHCP client ch mt vi giy cho mt offer, nu n khng nhn mt offer n s
rebroadcast (broadcast gi DHCPDISCOVER) trong khong thi gian l 2,4,8 v 16
giy.
Nu DHCP client khng nhn mt offer sau bn ln yu cu, n s dng mt
a ch IP trong khong [169.254.0.1 n 169.254.255.254] vi subnet mask l
[255.255.0.0]. N s s dng trong mt s trong khong IP v vic s gip cc
DHCP client trong mt mng khng c DHCP server thy nhau. DHCP client tip tc
c gng tm kim mt DHCP server sau mi 5 pht.
1.4.3. IP Lease Selection
DHCP client nhn c DHCP offer. N s phn hi broadcast li mt gi tin
DHCP request chp nhn ci offer . DHCP request bao gm cc thng tin v
DHCP cp a ch cho n. y DHCP client gi DHCP request nh mt thng bo
tm thy v chp nhn thu mt a ch IP t con DHCP server v thi khng cho
cc DHCP server khc gi cc DHCP offer trong trng hp h thng mng c nhiu
hn mt DHCP server.
1.4.4. IP Lease Acknowledgement
Khi DHCP server nhn c DHCP request s tr li DHCP client mt DHCP
ACK or NACK. cho bit l chp nhn cho DHCP client thu a ch IP. Gi
tin ny s bao gm a ch IP v cc thng tin cu hnh khc (DNS server, WINS
server, default getway). Khi DHCP client nhn c DHCP ACK or NACK th
chnh thc kt thc qu trnh xin, tm kim a ch IP ca DHCP client.
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Lu : Quy trnh xin, cp pht IP gia DHCP Client v DHCP Server tn hiu
truyn i l tn hiu Broadcast.
1.5. C ch t ng refrest li thi gian ng k (lease time).
Theo mc nh ca DHCP server th mi IP lease ch c c 8 ngy. Nu theo
nh mc nh (8 ngy) th mt DHCP client sau mt khong thi gian l 50% (tc l 4
ngy) n s t ng xin li IP address vi DHCP m n xin ban u. DHCP client
lc ny s gi mt DHCPREQUEST trc tip (unicast) n DHCP server m n xin
ban u.
Nu m DHCP server cn sng, n s gi li gi tin DHCPACK renew
ti DHCP client, gi ny bao gm thng s cu hnh mi cp nht nht trn DHCP
server.
Nu DHCP server cht th DHCP client s tip tc s dng cu hnh hin
thi ca n. V nu sau 87,5% (7 ngy) ca thi gian thu hin thi ca n, n s
broadcast mt DHCPDISCOVER update a ch IP ca n. Vo lc ny, n khng
tm ti DHCP server ban u cho n thu na m n l s chp nhn bt c mt DHCP
server no khc.
Nu thi gian lease ht, th client s ngay lp tc dng li vic s dng IP
address lease . V DHCP client sau s bt u tin trnh thu mt a ch nh ban
u.
Lu : Khi khi ng (restart) li DHCP client thi n s t ng renew li IP
address m trc khi n shutdown.
1.6. u im ca DHCP
1.6.1. Qun l TCP/IP tp trung
Thay v phi qun l a ch IP v cc tham s TCP/IP khc vo mt cun s
no (y l vic m qun tr mng phi lm khi cu hnh TCP/IP bng tay) th
DHCP server s qun l tp trung trn giao din ca n. Gip cc nh qun tr va d
qun l, cu hnh, khc phc khi c li xy ra trn cc my trm.
1.6.2. Gim gnh nng cho cc nh qun tr h thng
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Trc y cc nh qun tr mng thng phi nh cu hnh IP bng tay (gi l
IP tnh) nhng nay nh c DHCP server n s cp IP mt cch t ng cho cc my
trm. Nht l trong mi trng mng ln th s cn thit v hu ch ca dch v mng
ny mi thy r rng nht.
Vi kiu cu hnh bng tay th ngi dng c th thay i IP. Ngi th ty my
thch vc chi, c ngi thay i lung tung DNS server sau qun khng nh IP ca
DNS server l g t li cho ng li vi qun tr mng, c ngi t IP lm trng
vi IP ca ngi khc, ngi khc t IP trng vi Defaul Gateway ... lm cho qun tr
mng khn kh. Nhng kiu ny khng c IP ng. Ngi no thch thay i cng
chu. Ch c ngi qun tr DHCP server h mi c quyn thay i.
1.6.3. Gip h thng mng lun c duy tr n nh
a ch IP cp pht ng cho cc my trm ly t di IP cu hnh sn trn
DHCP server. Cc tham s (DG, DNS server ...) cng cp cho tt c cc my trm l
chnh xc. S trng lp IP khng bao gi xy ra. Cc my trm lun lun c mt cu
hnh TCP/IP chun. Lm cho h thng hot ng lin tc, va gim gnh nng cho
ngi qun tr va tng hiu qu lm vic cho user ni ring v doanh nghip ni
chung.
1.6.4. Linh hot v kh nng m rng
Ngi qun tr c th thay i cu hnh IP mt cch d dng khi c s h tng
mng thay i. Do lm tng s linh hot cho ngi qun tr mng. Ngoi ra DHCP
ph hp t mng nh n mng ln. N c th phc v 10 my khch cho n hng
ngn my khch.
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Nghin cu trin khai DHCP Server trn Ubuntu Server
CHNG 2: TRIN KHAI DHCP SERVER TRN UBUNTU SERVER
2.1. Chun b trc khi tin hnh trin khai
Chng trnh chy my o VMware 9.0.1
DHCP server: Ubuntu server 13.04 trn my o VMware
DHCP client: trn my o VMware: Windows XP, Ubuntu desktop 13.04, my
tht: Windows 8.1
2.2. Trin khai cu hnh
2.2.1. Trn Ubuntu Server
Bc 1: Ci t dch v DHCP server
# apt-get install isc-dhcp-server
Bc 2: t IP tnh cho cng eth0
# nano /etc/network/interfaces
Bc 3: Ch nh card mng eth0 dng cho isc-dhcp-server
# nano /etc/default/isc-dhcp-server
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Bc 4.1: Cu hnh DHCP Server cp IP theo di mng
# nano /etc/dhcp/dhcpd.conf
Dng 1-2: Mc nh Client c cp v s dng IP trong vng 600s ti a l
7200s;
Dng 3: Ghi li log trong qu trnh hot ng;
Dng 4: Subnet v netmask ca mng;
Dng 5: Di IP s cp cho Client t 172.16.1.10 n 172.16.1.20;
Dng 6: a ch broadcast ca mng;
Dng 7: Tn ca min l mangmaytinhk54.com;
Dng 8: Full name ca server l srv1.mangmaytinhk54.com;
Dng 9: a ch Routes hay Gateway ca mng;
Bc 4.2: Cu hnh DHCP cp IP tnh theo a ch MAC
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Dng 1: Hostname ca Client
Dng 2: a ch MAC ca Client
Dng 3: Quy nh DHCP Server cp cho Client IP duy nht l 172.16.1.111
Bc 5: Khi ng li dch v DHCP server:
# service isc-dhcp-server restart
2.2.2. Trn VMware
t li ch mng cho cc my o cng mt mng.
y t c 3 my mng VMnet5.
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Nghin cu trin khai DHCP Server trn Ubuntu Server
2.2.3. Trn Client Windows XP (VMware)
Bc 1: Cu hnh nhn IP ng t DHCP server
Bc 2: Vo Start \ Run g cmd
Bc 3: Gii phng a ch IP c ca Windows XP, dng lnh:
ipconfig /release
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Bc 4: Xin cp li a ch IP cho Windows XP, dng lnh:
ipconfig /renew
Kt qu Windows XP nhn IP t DHCP server trn Ubuntu server theo cch cu hnh
cp IP theo di mng:
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Nghin cu trin khai DHCP Server trn Ubuntu Server
2.2.4. Trn Client Ubuntu Desktop (VMware)
Bc 1: Vo Terminal
Bc 2: Cu hnh cho my nhn IP ng:
nano /etc/network/interfaces
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Bc 3: Xin cp li a ch IP cho Ubuntu Desktop
# ifdown eth0
# ifup eth0
Kt qu Ubuntu Desktop nhn IP t DHCP Server trn Ubuntu server theo cch cu
hnh IP tnh theo a ch MAC:
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Nghin cu trin khai DHCP Server trn Ubuntu Server
2.2.5. Trn my tht Windows 8.1
Bc 1: Vo Control Panel \ Network and Sharing Center \ Change adapter settings
Bc 2: Disable cc card mng ch gi li card VMnet1
Bc 3: Cu hnh nhn a ch IP ng ca card VMnet1
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Bc 4: Vo VMware chuyn card mng ca Ubuntu server thnh VMnet1
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Nghin cu trin khai DHCP Server trn Ubuntu Server
Bc 5: Tt DHCP ca mng VMnet1
Bc 6: T Windows 8.1, xin cp li IP t DHCP server
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Nghin cu trin khai DHCP Server trn Ubuntu Server
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