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CIS 192 - Lesson 3: Routing and Subnetting Quiz

Test your knowledge on routing and subnetting concepts in CIS 192 with this quiz. Answer questions about ARP cache entries, Wireshark display filters, and IP addresses.

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CIS 192 - Lesson 3: Routing and Subnetting Quiz

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  1. CIS 192 – Lesson 3 • Lesson Module Status • Slides – draft • Properties - done • Flashcards - • 1st minute quiz – done • Web Calendar summary – done • Web book pages – done • Commands – done • Howtos – • Skills pacing - na • Lab – done • Depot (VMs) – done • LOR code name paper strips

  2. CIS 192 - Lesson 3 Quiz • Please take out a blank piece of paper, switch off your monitor, close your books, put away your notes and answer these questions: • What does the C flag mean when viewing ARP cache entries with arp -n? • What Wireshark display filter would only show ARP or ICMP protocol packets? • With an IP address of 172.30.4.100 and a netmask of 255.255.0.0, what is the broadcast address?

  3. CIS 192 – Lesson 3 Routing and Subnetting

  4. CIS 192 – Lesson 1 Network Powerpoint slides Rick Graziani • Thanks to Rick Graziani for letting me use some of his great network slides for this course • Rick’s site: http://www.cabrillo.edu/~rgraziani/

  5. Questions on previous material

  6. CIS 192 - Lesson 3 • Questions? • Previous lesson material • Lab assignment • How this class works

  7. Dumb Terminals RARP • RARP, or Reverse Address Resolution Protocol. • Like ARP, used to map MAC address to IP addresses. • Unlike ARP, used by devices to find their own IP address, not MAC address. • What kind of device would not know its own IP address? • Dumb terminals are diskless workstations. • Diskless workstations have no permanent storage (like a hard drive) to store network configurations. • Dumb terminals will know their own MAC address because it’s burned in to the card, but they have to use RARP to find their IP. Rick Graziani graziani@cabrillo.edu

  8. RARP RARP: Reverse Address Resolution Protocol Overview RARP (Reverse Address Resolution Protocol) allows a physical machine in a local area network to request its IP address from a gateway server's Address Resolution Protocol (ARP) table or cache. A network administrator creates a table in a local area network's gateway router that maps the physical machine (or Media Access Control - MAC address) addresses to corresponding Internet Protocol addresses (IP address). When a new machine is set up, its RARP client program requests from the RARP server on the router to be sent its IP address. Assuming that an entry has been set up in the router table, the RARP server will return the IP address to the machine which can store it for future use. http://www.javvin.com/protocolRARP.html

  9. PAT Example 2 1 SP: 1331 NAT/PAT table maintains translation of: DA, SA, SP SP: 1555 translated 1 2

  10. PAT Example 3 4 SP: 1331 NAT/PAT table maintains translation of: SA (DA), DA (SA), DP (SP) SP: 1555 translated 4 3

  11. Housekeeping

  12. CIS 192 - Lesson 3 • Roll Call

  13. CIS 192 - Lesson 3 CIS 192 – Graded Work Graded work is copied to your home directories: [root@opus ~]# ls -l /home/cis192/gantden/ total 8 -r-------- 1 gantden staff 3013 Feb 19 23:16 lab01-graded.gantden [root@opus ~]#

  14. CIS 192 - Lesson 3 • Graded Lab Observations • Command summary sections should contain brief documented examples. For reference in future labs and after this course. • I will be using the vi editor to view and markup your submittals. Please make sure your text files display cleanly in vi.

  15. CIS 192 - Lesson 3 CIS 192 – Code Names Lord of the Rings Characters Code names are ready

  16. CIS 192 - Lesson 3 CIS 192 – Extra Credit Link to Extra Credit page is on the Grades page Note the caps on extra credit.

  17. Internships • Last week we met with local businesses. • Topic: paid and unpaid internships for Cabrillo CIS/CS students. • Cabrillo has resources for writing resumes, interviewing, job etiquette , etc. See: http://cabrillo.edu/services/jobs • Jobs mailing list: Subscribe by emailing (no subject or body): • networkers-subscribe@cabrillo.edu

  18. Permanent Network Configuration

  19. CIS 192 - Lesson 3 Configuring Network Settings Different ways to configure network settings • GUI tools • Permanent, • Different for each distribution • The ifconfig and route commands • Temporary (till next restart) • Editing configuration files and restarting the network service • Permanent • Some variations between distributions • Requires network service being restarted

  20. CIS 192 - Lesson 3 Configuring Permanent Network Settings (Red Hat Family) /etc/sysconfig/network-scripts/ifcfg-eth0 By the way - tab completes are wonderful

  21. CIS 192 - Lesson 3 Managing System Services (daemons) (Red Hat Family) • Manually starting and stopping • service --status-all • service xxxxxx <stop|start|restart|status> • System startup configuration • chkconfig --list • chkconfig [--level levels] xxxxxx <on|off> Show all services Control a specific service

  22. CIS 192 - Lesson 3 Configuring Permanent Network Settings (Red Hat Family) Restarting network services [root@elrond ~]# service network restart Shutting down interface eth0: [ OK ] Shutting down loopback interface: [ OK ] Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining IP information for eth0... done. [ OK ] [root@elrond ~]# /etc/init.d/network restart Shutting down interface eth0: [ OK ] Shutting down loopback interface: [ OK ] Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining IP information for eth0... done. [ OK ] or For Ubuntu 8.10: /etc/init.d/networking restart For OpenSUSE 11.1: rcnetwork restart

  23. CIS 192 - Lesson 3 Set Static IP Address and Subnet Mask (Red Hat Family) • Temporary • ifconfig eth0 172.30.4.125 netmask 255.255.255.0 broadcast 172.30.4.255 • Permanent • Edit /etc/sysconfig/network-scripts/ifcfg-eth0 • [root@elrond ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 • # Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE] • DEVICE=eth0 • ONBOOT=yes • HWADDR=00:0c:29:ba:63:76 • BOOTPROTO=static • IPADDR=172.30.4.125 • NETMASK=255.255.255.0 • BROADCAST=172.30.4.255 • [root@elrond ~]# • [root@elrond ~]# service network restart • Shutting down interface eth0: [ OK ] • Shutting down loopback interface: [ OK ] • Bringing up loopback interface: [ OK ] • Bringing up interface eth0: [ OK ] • [root@elrond ~]# Use tab completion when typing! There is a different file for each interface Add these static IP settings For new settings to take effect

  24. CIS 192 - Lesson 3 Set Static IP Address and Subnet Mask (Red Hat Family) • Verify • Use ifconfig and ping commands • [root@elrond ~]# ifconfig eth0 • eth0 Link encap:Ethernet HWaddr 00:0C:29:BA:63:76 • inet addr:172.30.4.125 Bcast:172.30.4.255 Mask:255.255.255.0 • inet6 addr: fe80::20c:29ff:feba:6376/64 Scope:Link • UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 • RX packets:556 errors:0 dropped:0 overruns:0 frame:0 • TX packets:495 errors:0 dropped:0 overruns:0 carrier:0 • collisions:0 txqueuelen:1000 • RX bytes:61635 (60.1 KiB) TX bytes:82641 (80.7 KiB) • Interrupt:177 Base address:0x1400 • [root@elrond ~]# ping -c 1 172.30.4.1 • PING 172.30.4.1 (172.30.4.1) 56(84) bytes of data. • 64 bytes from 172.30.4.1: icmp_seq=1 ttl=255 time=3.61 ms • --- 172.30.4.1 ping statistics --- • 1 packets transmitted, 1 received, 0% packet loss, time 0ms • rtt min/avg/max/mdev = 3.617/3.617/3.617/0.000 ms • [root@elrond ~]#

  25. CIS 192 - Lesson 3 Set Dynamic IP Address and Subnet Mask (Red Hat Family) • Temporary • dhclient and dhclient –r to release • Permanent • Edit /etc/sysconfig/network-scripts/ifcfg-eth0 • [root@elrond ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 • # Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE] • DEVICE=eth0 • ONBOOT=yes • HWADDR=00:0c:29:ba:63:76 • BOOTPROTO=dhcp • [root@elrond ~]# • [root@elrond ~]# service network restart • Shutting down interface eth0: [ OK ] • Shutting down loopback interface: [ OK ] • Bringing up loopback interface: [ OK ] • Bringing up interface eth0: [ OK ] • [root@elrond ~]# Use tab completion when typing! There is a different file for each interface Add this for DHCP For new settings to take effect

  26. CIS 192 - Lesson 3 Set Dynamic IP Address and Subnet Mask (Red Hat Family) • Verify • Use ifconfig and ping commands • [root@elrond ~]# ifconfig eth0 • eth0 Link encap:Ethernet HWaddr 00:0C:29:BA:63:76 • inet addr:172.30.4.168 Bcast:172.30.4.255 Mask:255.255.255.0 • inet6 addr: fe80::20c:29ff:feba:6376/64 Scope:Link • UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 • RX packets:3548 errors:0 dropped:0 overruns:0 frame:0 • TX packets:2135 errors:0 dropped:0 overruns:0 carrier:0 • collisions:0 txqueuelen:1000 • RX bytes:824033 (804.7 KiB) TX bytes:287392 (280.6 KiB) • Interrupt:177 Base address:0x1400 • [root@elrond ~]# ping -c 1 google.com • PING google.com (74.125.67.100) 56(84) bytes of data. • 64 bytes from gw-in-f100.google.com (74.125.67.100): icmp_seq=1 ttl=240 time=44.0 ms • --- google.com ping statistics --- • 1 packets transmitted, 1 received, 0% packet loss, time 0ms • rtt min/avg/max/mdev = 44.088/44.088/44.088/0.000 ms • [root@elrond ~]# Snickers will set the DNS server as well

  27. CIS 192 - Lesson 3 Set Dynamic IP Address and Subnet Mask (Red Hat Family) • Verify • Check if the DNS server was set • [root@elrond ~]# cat /etc/resolv.conf • ; generated by /sbin/dhclient-script • nameserver 207.62.187.54 • [root@elrond ~]# • [root@elrond ~]# route -n • Kernel IP routing table • Destination Gateway Genmask Flags Metric Ref Use Iface • 172.30.4.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 • 0.0.0.0 172.30.4.1 0.0.0.0 UG 0 0 0 eth0 • [root@elrond ~]# The lab DHCP server, Snickers, will set the DNS server and default gateway as well

  28. CIS 192 - Lesson 3 Tangent: dhclient command Using dhclient to get an IP address

  29. CIS 192 - Lesson 3 Tangent: dhclient command Using dhclient–r to release an IP address

  30. CIS 192 - Lesson 3 Configuring the default gateway (Red Hat Family) • Temporary • route add default gw 172.30.4.1 • Permanent • Edit /etc/sysconfig/network • [root@elrond ~]# cat /etc/sysconfig/network • NETWORKING=yes • NETWORKING_IPV6=no • HOSTNAME=elrond.localdomain • GATEWAY=172.30.4.1 • [root@elrond ~]# • [root@elrond ~]# service network restart • Shutting down interface eth0: [ OK ] • Shutting down loopback interface: [ OK ] • Bringing up loopback interface: [ OK ] • Bringing up interface eth0: [ OK ] • [root@elrond ~]# Add the gateway For new settings to take effect

  31. CIS 192 - Lesson 3 Configuring the default gateway (Red Hat Family) • Verify • Use route to verify • [root@elrond ~]# route -n • Kernel IP routing table • Destination Gateway Genmask Flags Metric Ref Use Iface • 172.30.4.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 • 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0 • 0.0.0.0 172.30.4.1 0.0.0.0 UG 0 0 0 eth0 • [root@elrond ~]# Default route to take

  32. CIS 192 - Lesson 3 Configuring the DNS • Permanent • Edit /etc/resolv.conf • [root@elrond ~]# cat /etc/resolv.conf • search cabrillo.edu • nameserver 207.62.187.54 • [root@elrond ~]# • Verify • Ping by hostname • [root@elrond ~]# ping -c 1 opus • PING opus.cabrillo.edu (207.62.186.9) 56(84) bytes of data. • 64 bytes from opus.cabrillo.edu (207.62.186.9): icmp_seq=1 ttl=63 time=3.67 ms • --- opus.cabrillo.edu ping statistics --- • 1 packets transmitted, 1 received, 0% packet loss, time 0ms • rtt min/avg/max/mdev = 3.671/3.671/3.671/0.000 ms • [root@elrond ~]# This will be appended to host names when trying to resolve them May add up to three of these for primary , secondary and tertiary DNS servers Note: On the ping, we can leave the .cabrillo.edu off the hostname since we have it in the search string in /etc/resolv.conf

  33. CIS 192 - Lesson 3 Configuring the hostname (Red Hat Family) • Permanent • Step 1 - edit /etc/sysconfig/network • [root@elrond ~]# cat /etc/sysconfig/network • NETWORKING=yes • NETWORKING_IPV6=no • HOSTNAME=homer.localdomain • GATEWAY=172.30.4.1 • [root@elrond ~]# init 6 change hostname Restart new hostname

  34. CIS 192 - Lesson 3 Configuring the hostname (Red Hat Family) • Permanent • Step 1 - edit /etc/hosts • [root@homer ~]# cat /etc/hosts • # Do not remove the following line, or various programs • # that require network functionality will fail. • 127.0.0.1 elrond.localdomain elrond localhost.localdomain localhost • ::1 localhost6.localdomain6 localhost6 • [root@homer ~]# • [root@homer ~]# cat /etc/hosts • # Do not remove the following line, or various programs • # that require network functionality will fail. • 127.0.0.1 homer.localdomain homer localhost.localdomain localhost • ::1 localhost6.localdomain6 localhost6 • [root@homer ~]# Be sure and update /etc/hosts with new hostname

  35. CIS 192 - Lesson 3 /etc/hosts [root@elrond ~]# cat /etc/hosts # Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 elrond.localdomain elrond localhost.localdomain localhost ::1 localhost6.localdomain6 localhost6 192.168.2.123 legolas 172.30.4.150 frodo 172.30.4.1 nosmo 192.168.3.200 sauron [root@elrond ~]# Use /etc/hosts to refer to hosts by name rather than IP address

  36. CIS 192 - Lesson 3 /etc/hosts using a name rather than an IP address [root@elrond ~]# ping nosmo PING nosmo (172.30.4.1) 56(84) bytes of data. 64 bytes from nosmo (172.30.4.1): icmp_seq=1 ttl=255 time=1.55 ms --- nosmo ping statistics --- 2 packets transmitted, 1 received, 50% packet loss, time 1001ms rtt min/avg/max/mdev = 1.554/1.554/1.554/0.000 ms [root@elrond ~]# ping sauron PING sauron (192.168.3.200) 56(84) bytes of data. 64 bytes from sauron (192.168.3.200): icmp_seq=1 ttl=63 time=1.61 ms --- sauron ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 1.616/1.616/1.616/0.000 ms [root@elrond ~]# /etc/hosts was updated with nosmo and sauron and their IP addresses

  37. CIS 192 - Lesson 3 Exercise • Revert Celebrian to its snapshot • Power on and change its hostname to celebrian-xx where xx is your station number. • Permanently set its eth0 interface to use DHCP • Permanently set eth1 with this static IP address: • 192.168.2.125 • 255.255.255.0 • Check that the default gateway (route –n) and DNS (cat /etc/resolv.conf) were correctly set by DHCP • Delete then add back in again the default gateway. • Add nosmo and station-xx (xx is your station number) to /etc/hosts and test it with ping nosmo and ping station-xx

  38. Routing

  39. Routers and the Network Layer Routers • Networking devices that make best path decisions (which interface to forward the IP packet) based in Layer 3 IP Destination Address. • Routers connect multiple networks. Directly Connected Networks Each interface connects to a different network. Each interface has an IP address/mask for that network. Rick Graziani graziani@cabrillo.edu

  40. CIS 192 - Lesson 3 Routers and the Network Layer Linux routers • Networking devices that make best path decisions (which interface to forward the IP packet) based in Layer 3 IP Destination Address. • Linux routers connect multiple networks. Directly Connected Networks Each interface connects to a different network. Each interface has an IP address/mask for that network. Rick Graziani modified by Rich Simms graziani@cabrillo.edu

  41. Routers belong to networks 192.168.10.1 255.255.255.252 Serial 0 Ethernet 0 Directly Connected Networks • Router interfaces must be members of different networks. • Router interfaces participate in the network like other hosts on that network. • Ethernet interfaces: • Have MAC Addresses • ARP Tables • Participate in the ARP Request and ARP Reply process like other hosts on that network. 172.16.1.1 255.255.255.0 MAC: 0cddeeffaabb Ethernet 1 172.16.2.1 255.255.255.0 MAC: 0abbccddeeff Rick Graziani graziani@cabrillo.edu

  42. CIS 192 - Lesson 3 Linux routers belong to networks 192.168.10.1 255.255.255.252 ppp0 172.16.1.1 255.255.255.0 MAC: 0cddeeffaabb Directly Connected Networks • Linux router interfaces must be members of different networks. • Router interfaces participate in the network like other hosts on that network. • Ethernet interfaces: • Have MAC Addresses • ARP Tables • Participate in the ARP Request and ARP Reply process like other hosts on that network. eth0 eth1 172.16.2.1 255.255.255.0 MAC: 0abbccddeeff Rick Graziani modified by Rich Simms graziani@cabrillo.edu

  43. Network Layer Routers • Make routing decisions based on Layer 3 information: • Destination IP address Rick Graziani graziani@cabrillo.edu

  44. Routed Protocols vs. Routing Protocols Rick Graziani graziani@cabrillo.edu

  45. Routed Protocol • IP is a routed protocol • A routed protocol is a layer 3 protocol that contains network addressing information. • This network addressing information is used by routers to determine the which interface, which next router, to forward this packet. Rick Graziani graziani@cabrillo.edu

  46. Routing Protocols • Protocols used by routers to build routing tables. • Routing tables are used by routers to forward packets. • RIP • IGRP and EIGRP • OSPF • IS-IS • BGP Rick Graziani graziani@cabrillo.edu

  47. Routing Types • A router must learn about non-directly connected networks either statically or dynamically. • Directly connected networks are networks that the router is connected to, has an IP address/mask. • Non-directly connected networks are remote networks connected to other routers. Rick Graziani graziani@cabrillo.edu

  48. Packet Forwarding

  49. Encapsulation Layer 3 IP Packet • Layer 3 packets are encapsulated into Layer 2 frames by the host. • Hubs: Only flood out the Layer 1 bits (repeater) • Switches: Examine only Layer 2 information: • Learn (Source MAC Address) • Forward (Destination MAC Address) • Layer 2 frames can be non-Ethernet frames, such as serial frames: • PPP, HDLC, Frame Relay, ATM, ISDN, etc. • Point-to-point serial frames (PPP, HDLC) are not multi-access networks and the Destination Address is many times just a layer 2 broadcast address. Layer 2 Data Link Frame Rick Graziani graziani@cabrillo.edu

  50. Encapsulation Layer 3 IP Packet • Routers: • Un-encapsulate Layer 3 packet from Layer 2 frame. • Lookup Layer 3 packet, Destination IP Address, in Routing Table. • Encapsulate Layer 3 packet into new Layer 2 frame and forward out proper (exit) interface. • Note: Destination IP Address and Source IP Address are not in their proper order. Layer 2 Data Link Frame Rick Graziani graziani@cabrillo.edu

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