CS615 - Aspects of System Administration

Transcription

1 CS615 - Aspects of System Administration Slide 1 CS615 - Aspects of System Administration Networking I Department of Computer Science Stevens Institute of Technology Jan Schaumann jschauma@stevens.edu

2 Networking I CS615 - Aspects of System Administration Slide 2

3 Networking I CS615 - Aspects of System Administration Slide 3

4 Layer 1: Repeater Hub CS615 - Aspects of System Administration Slide 4 Half-duplex, cheap, obsolete.

5 Layer 2: Network Switch CS615 - Aspects of System Administration Slide 5 MAC bridge, full-duplex, segmentation, STP

6 Layer 3: Router CS615 - Aspects of System Administration Slide 6 connect networks, forward packets, routing tables, BGP

7 CS615 - Aspects of System Administration Slide 7 IPv4 Basics IPv4 addresses are 32-bit numbers.

8 CS615 - Aspects of System Administration Slide 8 IPv4 Basics Each IPv4 address consists of four octets.

9 CS615 - Aspects of System Administration Slide 9 IPv4 Basics Each IPv4 address consists of four octets.

10 CS615 - Aspects of System Administration Slide 10 IPv4 Basics IPv4 addresses are divided into a network part and a host part. Hosts on the same network (broadcast domain) can talk to each other without the help of a router.

11 CS615 - Aspects of System Administration Slide 11 IPv4 Basics There are three different classes of IPv4 networks.

12 CS615 - Aspects of System Administration Slide 12 IPv4 Basics There are three different classes of IPv4 networks. Well, five, really.

13 IPv4 Basics CS615 - Aspects of System Administration Slide 13

14 CS615 - Aspects of System Administration Slide 14 Subnets A netmask splits the IPv4 address into network and host parts.

15 CS615 - Aspects of System Administration Slide 15 Subnets A netmask splits the IPv4 address into network and host parts.

16 Subnets CS615 - Aspects of System Administration Slide 16 $ ipcalc -n /16 Address: Netmask: = Wildcard: => Network: / HostMin: HostMax: Broadcast: Hosts/Net: Class B Try also: sipcalc -a /16

17 Subnets CS615 - Aspects of System Administration Slide 17 $ ipcalc -n /24 Address: Netmask: = Wildcard: => Network: / HostMin: HostMax: Broadcast: Hosts/Net: 254 Class B Try also: sipcalc -a /24

18 CIDR cheat sheet CS615 - Aspects of System Administration Slide 18 A.B.C.D/N N = bits describing network portion of address M = 32 N = bits in host portion of address 2 M = number of addresses on this subnet 2 M 2 = number of possible hosts first address on subnet = network address last address on subnet = broadcast address subnet division need not occur on dotted boundary only for example, you can divide /24 into four /26 networks networks starting at.0,.64,.128,.192 Which of the following is not a valid netmask? , ,

19 Mommy, where do IP addresses come from? CS615 - Aspects of System Administration Slide 19 The Internet Assigned Numbers Authority (IANA) oversees global IP address/as number allocation, root zone management etc.

20 Mommy, where do IP addresses come from? CS615 - Aspects of System Administration Slide 20 Regional Internet Registries (RIR) manage the allocation and registration of Internet number resources within a region of the world. XXX: put this in here somewhere

21 Mommy, where do IP addresses come from? CS615 - Aspects of System Administration Slide 21 RIRs assign blocks of IP addresses to the Local Internet Registries (LIR). LIRs are either ISPs, enterprises using a lot of addresses, or academic institutions.

22 IPv4 Subnets: Common CIDRs CS615 - Aspects of System Administration Slide /32 Host route /30 "Glue network" (Point-to-point) /29 Smallest multi-host network /28 Small LAN /27 Small LAN /26 Small LAN /25 Large LAN /24 Large LAN /20 Small ISP / Large business /19 LIR / ISP / Large business /18 LIR / ISP / Large business /17 LIR / ISP / Large business /16 LIR / ISP / Large business /8 RIR

23 IPv4 Exhaustion CS615 - Aspects of System Administration Slide 23

24 IPv4 Exhaustion CS615 - Aspects of System Administration Slide 24 IPv4 address space depletion: private IP space (RFC1918): /8, /12, /16 class D ( /4) and E ( /4) class As (16M addresses each!) initially handed out liberally (ATT, Apple, MIT, Stanford, Xerox,...) subnetting often inefficient more and more devices added

25 IPv4 Exhaustion CS615 - Aspects of System Administration Slide 25 IPv4 address space depletion: Total theoretically available IP addresses: 2 32 RFC1918: /8, /12, /16 RFC5735 etc.: /8, /10, /8, /16, /24, /24, /24, /15, /24, /24 Class D/E: /4, /4 Limited broadcast : /32 What is the percent/number of actually available IP addresses?

26 IPv4 Exhaustion CS615 - Aspects of System Administration Slide 26 Past and predicted: IANA Address Pool Exhaustion: APNIC reached final /8: RIPENCC reached final /8: LACNIC reached final /8: ARIN reached final /8: AFRINIC(predicted):

27 CS615 - Aspects of System Administration Slide 27 IPv6 Basics IPv4 addresses are 32-bit numbers.

28 CS615 - Aspects of System Administration Slide 28 IPv6 Basics IPv6 addresses are 128 bits.

29 CS615 - Aspects of System Administration Slide 29 IPv6 Basics IPv4: 32 bits => 2 32 addresses IPv6: 128 bits => addresses

30 CS615 - Aspects of System Administration Slide 30 IPv6 Basics IPv4: 32 bits => 4, 294, 967, 296 addresses IPv6: 128 bits => addresses

31 CS615 - Aspects of System Administration Slide 31 IPv6 Basics IPv4: 32 bits => 4, 294, 967, 296 addresses IPv6: 128 bits => 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses

32 IPv6 Basics CS615 - Aspects of System Administration Slide 32

33 IPv6 Basics CS615 - Aspects of System Administration Slide 33 8x16 bit fields (words) in case insensitive colon hexadecimal representation 2031:0000:0000:030F:0000:0000:0000:130B

34 IPv6 Basics CS615 - Aspects of System Administration Slide 34 8x16 bit fields (words) in case insensitive colon hexadecimal representation 2031:0000:0000:030F:0000:0000:0000:130B Leading zeros in a field are optional: 2031:0:0:30F:0:0:0:130B

35 IPv6 Basics CS615 - Aspects of System Administration Slide 35 8x16 bit fields (words) in case insensitive colon hexadecimal representation 2031:0000:0000:030F:0000:0000:0000:130B Leading zeros in a field are optional: 2031:0:0:30F:0:0:0:130B Successive fields of 0 represented as ::, but only once in an address: 2031::30F:0:0:0:130B 2031:0:0:30F::130B 2031::30F::130B ok ok not ok

36 IPv6 Basics CS615 - Aspects of System Administration Slide 36 8x16 bit fields (words) in case insensitive colon hexadecimal representation 2031:0000:0000:030F:0000:0000:0000:130B Leading zeros in a field are optional: 2031:0:0:30F:0:0:0:130B Successive fields of 0 represented as ::, but only once in an address: 2031::30F:0:0:0:130B 2031:0:0:30F::130B 2031::30F::130B ok ok not ok 0000:0000:0000:0000:0000:0000:0000:00001 => 0:0:0:0:0:0:0:1 => ::1

37 IPv6 Basics - Address Oddities CS615 - Aspects of System Administration Slide 37 Address may include a link name: 2001:470:1f07:3d1::1%eth0

38 IPv6 Basics - Address Oddities CS615 - Aspects of System Administration Slide 38 Address may include a link name: 2001:470:1f07:3d1::1%eth0 IPv4-mapped addresses 0:0:0:0:0:ffff: ::ffff:

39 IPv6 Basics - Address Oddities CS615 - Aspects of System Administration Slide 39 Address may include a link name: 2001:470:1f07:3d1::1%eth0 IPv4-mapped addresses 0:0:0:0:0:ffff: ::ffff: You need brackets to distinguish a port from an address: IPv4: :22 IPv6: [2001:470:1f07:3d1::1]:22

40 IPv6 Basics Address Scope CS615 - Aspects of System Administration Slide 40 Link-Local (example: fe80::e276:63ff:fe72:3900%xennet0) Used on a single link Packets with link-local source or destination addresses are not forwarded to other links

41 IPv6 Basics Address Scope CS615 - Aspects of System Administration Slide 41 Link-Local (example: fe80::e276:63ff:fe72:3900%xennet0) Used on a single link Packets with link-local source or destination addresses are not forwarded to other links Unique-Local (fc00::/7) Used for private IPv6 networks not globally routable Applications similar to RFC 1918

42 IPv6 Basics Address Scope CS615 - Aspects of System Administration Slide 42 Link-Local (example: fe80::e276:63ff:fe72:3900%xennet0) Used on a single link Packets with link-local source or destination addresses are not forwarded to other links Unique-Local (fc00::/7) Used for private IPv6 networks not globally routable Applications similar to RFC 1918 Global (example: 2001:470:1f07:3d1::1) A globally unique address Packets with global addresses can be forwarded to any part of the global network

43 IPv6 Subnets CS615 - Aspects of System Administration Slide 43 $ sipcalc 2001:470:30:84:e276:63ff:fe72:3900/64 -[ipv6 : 2001:470:30:84:e276:63ff:fe72:3900/64] - 0 [IPV6 INFO] Expanded Address :0470:0030:0084:e276:63ff:fe72:3900 Compressed address :470:30:84:e276:63ff:fe72:3900 Subnet prefix (masked) :470:30:84:0:0:0:0/64 Address ID (masked) - 0:0:0:0:e276:63ff:fe72:3900/64 Prefix address - ffff:ffff:ffff:ffff:0:0:0:0 Prefix length - 64 Address type - Aggregatable Global Unicast Addresses Network range :0470:0030:0084:0000:0000:0000: :0470:0030:0084:ffff:ffff:ffff:ffff

44 CS615 - Aspects of System Administration Slide 44 IPv6 Subnets: Common CIDRs 2001:0db8:0123:4567:89ab:cdef:1234: Single end-points and loopback Single End-user LAN (default prefix size for SLAAC) Proposed minimal end sites assignment Default end sites assignment Local Internet registry minimum allocations 28 Local Internet registry medium allocations 24 Local Internet registry large allocations 20 Local Internet registry extra large allocations Regional Internet Registry allocations from IANA 8

45 Networking Buzzwords CS615 - Aspects of System Administration Slide 45 The network is the computer. John Gage, Sun Microsystems

46 Networking Buzzwords CS615 - Aspects of System Administration Slide 46 The network is the network, the computer is the computer - sorry about the confusion. Joe on Computing

47 Networking Buzzwords CS615 - Aspects of System Administration Slide 47

48 Networking CS615 - Aspects of System Administration Slide 48

49 Networking CS615 - Aspects of System Administration Slide 49 /X?

50 Networking CS615 - Aspects of System Administration Slide 50 /X?

51 Networking CS615 - Aspects of System Administration Slide 51

52 CS615 - Aspects of System Administration Slide 52 WHOIS ASN? The Internet Assigned Numbers Authority (IANA) oversees global IP address/as number allocation, root zone management etc.

53 WHOIS ASN? CS615 - Aspects of System Administration Slide 53 Autonomous System Numbers (ASNs) are assigned by IANA to the RIRs, see e.g. ftp://ftp.arin.net/pub/stats/arin/ You can query databases on the internet about e.g. IP block or ASN information via the WHOIS protocol: $ whois more NetRange: CIDR: /16 NetName: STEVENS NetHandle: NET Parent: NET155 (NET ) NetType: Direct Assignment Organization: Stevens Institute of Technology (SIT) RegDate: Updated: Ref:

54 WHOIS ASN? CS615 - Aspects of System Administration Slide 54 Carriers connect their Autonomous Systems at Internet Exchange Points (IXPs) to route traffic between the different networks. This peering happens amongst carriers on a tiered basis. Examples:

55 WHOIS ASN? CS615 - Aspects of System Administration Slide 55 Most of these services are available via APIs or text-based interfaces: $ host has address has IPv6 address 2607:f8b0:4006:807::2004 $ whois -h whois.cymru.com 2607:f8b0:4006:807::2004 AS IP AS Name :f8b0:4006:807::2004 GOOGLE - Google Inc., US $ curl -s python -mjson.tool more { "data": [ { "aka": "Google, YouTube (for Google Fiber see AS16591 record)", "created": " T06:41:04Z", "id": 433, "info_ipv6": true, "info_prefixes4": 15000, "info_prefixes6": 750, "info_ratio": "Mostly Outbound",

56 Networking CS615 - Aspects of System Administration Slide 56

57 Networking CS615 - Aspects of System Administration Slide 57

58 Networking CS615 - Aspects of System Administration Slide 58 To find the path your packets might take, give traceroute(1) a go: $ traceroute search.yahoo.com traceroute to search.yahoo.com ( ), 30 hops max, 60 byte packets ( ) ms postal0.cs.stevens-tech.edu ( ) ( ) ms ms gwa.cc.stevens.edu ( a0465.cst.lightpath.net ( ) ms ms ms cst.lightpath.net ( ) ms ms ms 5 hunt optonline.net ( ) ms ms cst.ligh 6 451be0a9.cst.lightpath.net ( ) ms ms hunt optonl 7 nyiix.bas1-m.nyc.yahoo.com ( ) ms 451be0a9.cst.lightpath.net 8 ae-1.pat2.bfw.yahoo.com ( ) ms ae-1.pat1.bfw.yahoo.com ( et msr1.bf2.yahoo.com ( ) ms et msr2.bf1.yahoo.co 10 et clr1-a-gdc.bf1.yahoo.com ( ) ms et clr2-a-gdc.bf1

59 Networking CS615 - Aspects of System Administration Slide 59

60 Networking CS615 - Aspects of System Administration Slide 60

61 Networking CS615 - Aspects of System Administration Slide 61

62 Networking CS615 - Aspects of System Administration Slide 62 Stringing cables across the oceans floors since 1866!

63 Networking CS615 - Aspects of System Administration Slide 63

64 Networking CS615 - Aspects of System Administration Slide 64 The Net interprets censorship as damage and routes around it....except when it can t.

65 Networking CS615 - Aspects of System Administration Slide

66 Networking CS615 - Aspects of System Administration Slide 66 The internet is a physical place A

67 Networking CS615 - Aspects of System Administration Slide 67 Now identify the physical and organizational aspects of your network traffic: $ traceroute search.yahoo.com traceroute to search.yahoo.com ( ), 30 hops max, 60 byte packets ( ) ms postal0.cs.stevens-tech.edu ( ) ( ) ms ms gwa.cc.stevens.edu ( a0465.cst.lightpath.net ( ) ms ms ms cst.lightpath.net ( ) ms ms ms 5 hunt optonline.net ( ) ms ms cst.ligh 6 451be0a9.cst.lightpath.net ( ) ms ms hunt optonl 7 nyiix.bas1-m.nyc.yahoo.com ( ) ms 451be0a9.cst.lightpath.net 8 ae-1.pat2.bfw.yahoo.com ( ) ms ae-1.pat1.bfw.yahoo.com ( et msr1.bf2.yahoo.com ( ) ms et msr2.bf1.yahoo.co 10 et clr1-a-gdc.bf1.yahoo.com ( ) ms et clr2-a-gdc.bf1

68 Networking I CS615 - Aspects of System Administration Slide 68

69 Internet Maps and Architecture CS615 - Aspects of System Administration Slide

70 IPv6 CS615 - Aspects of System Administration Slide