retele de calculatoare - linux

Reţele Reţele

JICA (Japan International Cooperation Agency)

Voluntar Yasuyuki Shimura02.06.2006

2

Bază

Cursul de S.O. LinuxCursul de S.O. LinuxRelaţiile dintre lecţii

Server

Linux

Reţea

avansat ExerciţiuIntroducere

Prezentare Linux

Folosirea de comenzi

de stabilit

SecuritateConcept reţea(TCP/IP)

Management sistem

Management operaţie

Construcţie de reţea

ManagementReţea

astăzi

3

Cuprins şi Scopurile lecţiei de astăziCuprins şi Scopurile lecţiei de astăzi

Cuprins1. Recapitulare (Conceptul „TCP/IP”, Aparat de reţea, Securitate)2. Comenzile pentru reţea3. Design de reţea

Scopurile lecţiei de astăzi[Practică]

1. Comenzile pentru reţea.2. Design de reţea.

4

Recapiturale de conceptul „TCP/IP”Recapiturale de conceptul „TCP/IP”TCP/IP stivă de protocoale

Fizic

Regătură de date

Reţea

Transport

Sesiune

Prezentare

Aplicaţie Aplicaţie

Transport

Reţea

Interfaţă de reţea

SMTPHTTP/HTTPS

POP3 SNMPetc.

TCP

FTP

IP

Ethernet ATM PPP Etc

OSI model strat de „TCP/IP stack”

Exemplu de TCP/IP protocol stack

ICMP

ARPRARP

Protocol Set de proceduri pentru a permite calculatoarelor să se conecteze între ele şi să facă schimb de informaţii

5

Recapiturale de conceptul „TCP/IP”Recapiturale de conceptul „TCP/IP”Ce este protocol de IP?

Pentru a comunica între calculatoare, adresa este organizată de1. „IP Address”2. „Subnet mask”(mască subreţelei)3. „Default Gateway”(poartă prestabilită)

Se divizează datele transmise în date mai mici care se numesc „pachete”

Se adaugă adrese pachetelor (Adresa de IP(IP Address))

Se pot comunica pachetele între reţele fizice diferite(Direcţionare(Routare))

„IP Address” este adresa alocată pe placă de reţea(nu pe calculator)

„Subnet mask” defineşte reţeaua careia calculatoarele îi aparţin

„Default Gateway” este adresa de destinaţie careia mai întâi pachetele îi sunt trimise, când adresa de destinaţie finală nu aparţine reţelei careia îi aparţine adresa de expediţie

6

Recapiturale de conceptul „TCP/IP” şi aparate pt. reteaRecapiturale de conceptul „TCP/IP” şi aparate pt. reteaCe este protocol de TCP?(Despre funcţiile de protocol de TCP)

1. Prin protocol, datele sunt transferate cu siguranţă.2. Date transferate ajunge cu ordine.

Cum funcţionează protocolul „TCP”?

Trebuie să pregătească aparat pentru reţea. Aparate principale sunt precum urmează.(pentru „intranet”)

1. „Hub” şi „Switching Hub”2. „Router”(pentru a accede internet)3. „cable”

În protocolul de „TCP”, se comunică prin „port”-uri.

„port” specific servicii(programare sau „daemon”)

7

Recapiturale de securitateRecapiturale de securitateRemediu împotriva amenintărilor

interceptare electrică(electric interception)

falsificare(falsification)

joacă(impersonation)

folosire abuzivă

sustragere

virus

Face „backup” regulat.

Criptarea datelor(folosind „SSH(Secure Shell)”şi „SSL”

Setează alte drepturi asupra fişierelor şi directoarelor faţă de cele corecte.Utilizator gestionează „ID” şi „Password” serios.

Face controlul accesului folosind „id”, „password”,numele calculatorului şi adresa de IP.(tcpwrapper etc.)Nu lansa programe inutile.

Face actualizarea securităţii(„security update”) reglate

Face filtrarea pachetelor(„pachet filtering”) tot timpul.(ipfilter)

Instalează soft antivirus care scanează la accesarea acestora

8

Comenzi pentru reţeaComenzi pentru reţeaPentru a gestiona reţeaua, se folosesc comenzi precum urmează.

1. ifconfig/ipconfig2. ping3. traceroute(tracert)4. dig/nslookup

Cum se setează placă de reţea?

ifconfig A configura parametru de placă de reţea

Confirmarea setărilor

ifconfig -a

Setarea pe placă de reţea

ifconfig [numele „device”] [adresa de IP] netmask [„subnet mask”]

Pornirea şi oprirea placii de reţea

ifconfig [numele „device”] up

ifconfig [numele „device”] down*ifconfig are multe opţiuni, referiţi „man”

9

Comenzi pentru reţeaComenzi pentru reţeaCe este ping?

Ce este traceroute?(În windows, se foloseşte „tracert”)

Ce este nslookup/dig?

ping [adresa de IP sau numele calculatorului]

Aceasta comandă confirmă existenţa conexiunii între calculatoare

traceroute [adresa de IP sau numele calculatorului]

Aceasta comandă confirmă fluxul de pachete(adică routare)

nslookup [adresa de IP sau numele calculatorului]

Aceasta comandă confirmă dacă se poate căuta adresa de IP plecând de la nume sau numele plecând de la adresa de IP

dig [adresa de IP sau numele calculatorului]

10

Design de reţeaDesign de reţeaÎntrebare 1Desenaţi linii care reprezintă cablu pentru ca orice calculator să conecteze la internet

cablu legaturi directecablu legaturi inversate

Legendă

placă de reţea

hub routerhub

DNS/MailServer

calculatorcalculator

calculator

Reţea exterioară

11

Design de reţeaDesign de reţeaRăspuns 1

hub routerhub

DNS/MailServer


calculator


Legendă

placă de reţea

Reţea exterioară

12

Design de reţeaDesign de reţeaÎntrebare 2:Scrieţi adresa de IP, Subnet mask, Default gateway, DNS. Dar eu pre-definesc placa de reţea din reţeaua exterioară în avans. Iar despre default gateway, specificaţi serverul DNS din reţea interioară.

router

hubDNS/MailServer


calculator

Reţea interioară 192.168.2.0/24 100Mbps

IP Sub DG DNS

IP Sub DG DNS

IP Sub DG 1.2.3.1 DNS

IP 1.2.3.4 Sub 255.255.255.0 DG 1.2.3.1 DNS 1.2.3.2

IP Sub DG DNS

IP Sub DG DNS

Reţea exterioară1.2.3.0/2410Mbps

Legendă


placă de reţea

13

Design de reţeaDesign de reţeaRăspuns 2(Exemplu).

router

hubDNS/MailServer


calculator


IP 192.168.2.101Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.20Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 1.2.3.4 Sub 255.255.255.0 DG 1.2.3.1 DNS 1.2.3.2

IP 192.168.2.102Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.103Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20


IP 192.168.2.10Sub 255.255.255.0DG 1.2.3.1DNS 192.168.2.20

Legendă


placă de reţea

14

Design de reţeaDesign de reţeaÎntrebare 3:Dispuneţi softuri precum urmează pentru securitate: Firewall, Antivirus, SSL, tcpwrapper

router

hubDNS/MailServer


calculator


IP 192.168.2.101Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.20Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 1.2.3.4 Sub 255.255.255.0 DG 1.2.3.1 DNS 1.2.3.2

IP 192.168.2.102Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.103Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20


IP 192.168.2.10Sub 255.255.255.0DG 1.2.3.1DNS 192.168.2.20

Legendă


placă de reţea

15

Design de reţeaDesign de reţeaRăspuns 3:

router

hubDNS/MailServer


calculator


IP 192.168.2.101Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.20Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 1.2.3.4 Sub 255.255.255.0 DG 1.2.3.1 DNS 1.2.3.2

IP 192.168.2.102Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20

IP 192.168.2.103Sub 255.255.255.0DG 192.168.2.10 DNS 192.168.2.20


IP 192.168.2.10Sub 255.255.255.0DG 1.2.3.1DNS 192.168.2.20

firewall(ipfilter )tcpwrapper

Anti-virusSSL

firewallAnti-virus

firewallAnti-virus

firewallAnti-virus

firewall(ipfilter )tcpwrapper

Anti-virus

Legendă


placă de reţea

ipconfig• Confirmarea setărilor

root@0[knoppix]# ifconfig -aeth0 Link encap:Ethernet HWaddr 00:0D:60:F0:33:EC inet addr:172.16.0.165 Bcast:172.16.0.255 Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:153 errors:0 dropped:0 overruns:0 frame:0 TX packets:3 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:18580 (18.1 KiB) TX bytes:1026 (1.0 KiB)

lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:12 errors:0 dropped:0 overruns:0 frame:0 TX packets:12 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:600 (600.0 b) TX bytes:600 (600.0 b)

• Setarea pentru placa de reţearoot@0[knoppix]# ifconfig eth0 172.16.0.165 netmask 255.255.0.0

• Pornirea şi oprirea plăcii de reţearoot@0[knoppix]# ifconfig eth0 downroot@0[knoppix]# ifconfig -aeth0 Link encap:Ethernet HWaddr 00:0D:60:F0:33:EC inet addr:172.16.0.165 Bcast:172.16.0.255 Mask:255.255.0.0 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:289 errors:0 dropped:0 overruns:0 frame:0 TX packets:7 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:33586 (32.7 KiB) TX bytes:1362 (1.3 KiB)↑Nu exista şir de caracter „UP”

lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:12 errors:0 dropped:0 overruns:0 frame:0 TX packets:12 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:600 (600.0 b) TX bytes:600 (600.0 b)root@0[knoppix]# ifconfig eth0 uproot@0[knoppix]# ifconfig -aeth0 Link encap:Ethernet HWaddr 00:0D:60:F0:33:EC inet addr:172.16.0.165 Bcast:172.16.0.255 Mask:255.255.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:289 errors:0 dropped:0 overruns:0 frame:0 TX packets:7 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:33586 (32.7 KiB) TX bytes:1362 (1.3 KiB)lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:12 errors:0 dropped:0 overruns:0 frame:0 TX packets:12 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:600 (600.0 b) TX bytes:600 (600.0 b)

ping• Confirmarea legaturii la reţea

root@0[knoppix]# ping 172.16.0.135PING 172.16.0.135 (172.16.0.135): 56 data bytes64 bytes from 172.16.0.135: icmp_seq=0 ttl=255 time=1.5 ms64 bytes from 172.16.0.135: icmp_seq=1 ttl=255 time=0.1 ms64 bytes from 172.16.0.135: icmp_seq=2 ttl=255 time=0.5 ms--- 172.16.0.135 ping statistics ---3 packets transmitted, 3 packets received, 0% packet lossround-trip min/avg/max = 0.1/0.7/1.5 msroot@0[knoppix]# ping www.yahoo.comPING www.yahoo.akadns.net (216.109.118.74): 56 data bytes64 bytes from 216.109.118.74: icmp_seq=0 ttl=56 time=126.1 ms64 bytes from 216.109.118.74: icmp_seq=1 ttl=56 time=125.4 ms64 bytes from 216.109.118.74: icmp_seq=2 ttl=56 time=185.3 ms--- www.yahoo.akadns.net ping statistics ---3 packets transmitted, 3 packets received, 0% packet lossround-trip min/avg/max = 125.4/145.6/185.3 ms

root@0[knoppix]# ifconfig eth0 downroot@0[knoppix]# ping www.yahoo.comping: unknown host www.yahoo.comroot@0[knoppix]# ping 216.109.118.74PING 216.109.118.74 (216.109.118.74): 56 data bytesping: sendto: Network is unreachableping: wrote 216.109.118.74 64 chars, ret=-1--- 216.109.118.74 ping statistics ---4 packets transmitted, 0 packets received, 100% packet loss

traceroute• Confirmarea routări

root@0[knoppix]# traceroute www.yahoo.comtraceroute: Warning: www.yahoo.com has multiple addresses; using 216.109.118.67traceroute to www.yahoo.akadns.net (216.109.118.67), 30 hops max, 38byte packets 1 172.16.0.135 (172.16.0.135) 0.165 ms 0.188 ms 0.121 ms 2 r-thor-cr0-fe2-vl700-0.botosani.rdsnet.ro (80.96.86.65) 1.019 ms0.894 ms 0.829 ms 3 r-botosani-bb1-e0-0.botosani.rdsnet.ro (81.196.145.253) 1.886 ms1.316 ms 1.788 ms 4 br01.frankfurt.rdsnet.ro (193.231.252.33) 36.241 ms 35.706 ms 35.044 ms 5 br01.frankfurt.rdsnet.ro (193.231.252.33) 35.995 ms 35.363 ms 34.866 ms 6 ge-5-1-0.100.ar2.FRA3.gblx.net (64.210.28.93) 124.931 ms 69.703ms 70.292 ms 7 so2-1-0-2488M.ar1.DCA3.gblx.net (67.17.67.57) 143.549 ms 125.619ms 124.714 ms 8 yahoo-2.ar1.DCA3.gblx.net (208.51.74.182) 125.194 msyahoo-1.ar1.DCA3.gblx.net (208.50.13.210) 125.674 msyahoo-2.ar1.DCA3.gblx.net (208.51.74.182) 150.928 ms 9 ge-1-0-0-p110.msr2.dcn.yahoo.com (216.115.108.45) 123.257 msge-0-0-0-p100.msr1.dcn.yahoo.com (216.115.108.1) 123.065 msge-1-0-0-p111.msr2.dcn.yahoo.com (216.115.108.47) 123.166 ms10 ge3-1.bas1-m.dcn.yahoo.com (216.109.120.149) 128.270 msge7-2.bas2-m.dcn.yahoo.com (216.109.120.197) 123.251 msge3-1.bas2-m.dcn.yahoo.com (216.109.120.146) 125.701 ms11 p4.www.dcn.yahoo.com (216.109.118.67) 146.936 ms 137.989 ms 123.683 ms

nslookup şi dig• confirmarea funcţiei de DNS(Domain name server)

root@0[knoppix]# nslookup www.yahoo.comServer: 194.105.8.1Address: 194.105.8.1#53Non-authoritative answer:www.yahoo.com canonical name = www.yahoo.akadns.net.Name: www.yahoo.akadns.netAddress: 216.109.118.74Name: www.yahoo.akadns.netAddress: 216.109.118.79Name: www.yahoo.akadns.netAddress: 216.109.117.205Name: www.yahoo.akadns.netAddress: 216.109.117.106Name: www.yahoo.akadns.netAddress: 216.109.118.69Name: www.yahoo.akadns.netAddress: 216.109.118.75Name: www.yahoo.akadns.netAddress: 216.109.117.110Name: www.yahoo.akadns.netAddress: 216.109.118.71root@0[knoppix]# nslookup 216.109.118.74Server: 194.105.8.1Address: 194.105.8.1#5374.118.109.216.in-addr.arpa name = p11.www.dcn.yahoo.com.

root@0[knoppix]# dig www.yahoo.com; <<>> DiG 9.3.1 <<>> www.yahoo.com;; global options: printcmd;; Got answer:;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10277;; flags: qr rd ra; QUERY: 1, ANSWER: 9, AUTHORITY: 9, ADDITIONAL: 9;; QUESTION SECTION:;www.yahoo.com. IN A;; ANSWER SECTION:www.yahoo.com. 260 IN CNAME www.yahoo.akadns.net.www.yahoo.akadns.net. 20 IN A 216.109.117.110www.yahoo.akadns.net. 20 IN A 216.109.118.71www.yahoo.akadns.net. 20 IN A 216.109.118.74www.yahoo.akadns.net. 20 IN A 216.109.118.79www.yahoo.akadns.net. 20 IN A 216.109.117.205www.yahoo.akadns.net. 20 IN A 216.109.117.106www.yahoo.akadns.net. 20 IN A 216.109.118.69www.yahoo.akadns.net. 20 IN A 216.109.118.75;; AUTHORITY SECTION:akadns.net. 161811 IN NS asia4.akadns.net.akadns.net. 161811 IN NS asia9.akadns.net.akadns.net. 161811 IN NS eur4.akadns.net.akadns.net. 161811 IN NS eur8.akadns.net.akadns.net. 161811 IN NS usw5.akadns.net.akadns.net. 161811 IN NS za.akadns.org.akadns.net. 161811 IN NS zb.akadns.org.akadns.net. 161811 IN NS zc.akadns.org.akadns.net. 161811 IN NS zd.akadns.org.;; ADDITIONAL SECTION:asia4.akadns.net. 8213 IN A 61.213.147.96asia9.akadns.net. 161811 IN A 220.73.220.4eur4.akadns.net. 161811 IN A 195.219.3.169eur8.akadns.net. 8213 IN A 62.4.69.96usw5.akadns.net. 161811 IN A 63.241.73.200za.akadns.org. 3421 IN A 81.52.250.134zb.akadns.org. 3421 IN A 206.132.100.105zc.akadns.org. 3421 IN A 69.45.78.3zd.akadns.org. 3421 IN A 65.203.234.28;; Query time: 5 msec

;; SERVER: 194.105.8.1#53(194.105.8.1);; WHEN: Wed May 31 14:54:34 2006;; MSG SIZE rcvd: 512

root@0[knoppix]# dig 216.109.118.74; <<>> DiG 9.3.1 <<>> 216.109.118.74;; global options: printcmd;; Got answer:;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 59908;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0;; QUESTION SECTION:;216.109.118.74. IN A;; AUTHORITY SECTION:. 10800 IN SOA A.ROOT-SERVERS.NET.NSTLD.VERISIGN-GRS.COM. 2006053001 1800 900 604800 86400;; Query time: 138 msec;; SERVER: 194.105.8.1#53(194.105.8.1);; WHEN: Wed May 31 14:55:26 2006;; MSG SIZE rcvd: 107

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