Esercitazione re- di accesso

Transcription

1 Esercitazione re- di accesso

2 Outline Linux the Survivor Kit Netkit The poor man's system to experiment computer networking IpRoute2 show / manipulate rou-ng, devices, policy rou-ng and tunnels Wireshark network analyzer and sniffer

3 Why Linux? Open Source Philosophy: no secret for the user Widely used in networks Routers Embedded systems Servers Free distribu-on Large support and documenta-on and User Mode Linux

4 Linux in a nutshell FS Driver Kernel Net Scheduler shell $ o # Opera-ng System Desktop Environment (KDE, Gnome..) Slackware Debian Ubuntu glibc GCC Base U-ls(GNU) Services/daemons Mandriva Programs Packet Manager (apt, portage, rpm ) Arch Fedora Games Office (e.g. OpenOffice) Graphics (e.g. Gimp) Live Distro (e.g. Knoppix) Distribu-ons Others Suse Red Hat Gentoo

5 Support The Magic Word man Documenta-on Linux User Guide hep:// Distro Specific guides (e.g. hep://help.ubuntu it.org/ ) Linux User Group hep:// Download the netkit live distribu-on: hep://stud.netgroup.uniroma2.it/~donato.baeaglino/knoppix_netkit/knoppix.iso

6 Linux and Networking User Space System calls:socket Kernel Space Drivers Hardware Applica'on Transport Network Data Link Physical Interface Mapping eth0 eth1

7 Outline Linux the Survivor Kit Netkit The poor man's system to experiment computer networking IpRoute2 show / manipulate rou-ng, devices, policy rou-ng and tunnels Wireshark network analyzer and sniffer

8 Simula-on vs. Emula-on Emula-on and simula-on systems put at user s disposal a virtual environment that can be exploited for tests, experiments, measures SIMULATION EMULATION simula-on systems aim at reproducing the performanceof a real life system (latency -me, packet loss, etc.) e.g.: ns, real, emula-on systems aim at accurately reproducing the func-onali-esof a real life system (configura-ons, architectures, protocols), with limited aeen-on to performance References: hep:// labs/netkit_introduc-on/netkit introduc-on.pdf

9 Netkit The poor man's system to experiment computer networking WHAT S NETKIT: a system for emula-ng computer networks based on uml (user mode linux) user mode linux is a linux kernel (inner part of the linux os) that can be executed as a user process on a standard linux box a user mode linux process is also called virtual machine (vm), while the linux box that hosts a virtual machine is called host machine (host) each emulated network device is a virtual linux box note: the linux os is shipped with sojware suppor-ng most of the network protocols hence, any linux machine can be configured to act as a bridge/switch or as a router

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11 Sekng up and using Netkit Switch on your PC and insert the live CD + For further informa-on see at the netkit introduc-on.pdf

12 Sekng up a Netkit Lab Netkit Lab: automa-ze mul-ple virtual machine startup. To create a lab are needed: a lab configura-on file describing the network topology a set of subdirectoriesth at contain the configura-on sekngs for each virtual machine.startupand.shutdownfiles that describe ac-ons performed by virtual machines when they are started or halted [op-onally] a lab.depfile describing dependency rela-onships on the startup order of virtual machines

13 Outline Linux the Survivor Kit Netkit The poor man's system to experiment computer networking IpRoute2 show / manipulate rou-ng, devices, policy rou-ng and tunnels Wireshark network analyzer and sniffer

14 Simple and basic guide: h<p:// it/ip/ip4dummies/ IPRoute2 Implemented on almost any linux box with kernel > 2.2.X Mangle almost any network stuff: Interface sekng up and drop down Rou-ng Tables Arp Tables And more Mul-ple rou-ng tables Policy Rou-ng Tunnels NAT Replace old (but s-ll used) commands: route, arp, ifconfig Syntax (man ip) : ip [ OPTIONS ] OBJECT { COMMAND help } OBJECT := { link addr route rule neigh tunnel maddr mroute monitor } OPTIONS := { V[ersion] s[ta-s-cs] r[esolve] f[amily] { inet inet6 ipx dnet link } o[neline] }

15 IpRoute2: basic usage ip link set eth0 up Ac-vate eth0 interface ip addr add /24 dev eth0 Set an Ip to eth0 and setup an entry in the rou-ng table ip route add default via ip route add /16 via Ip link set eth0 address MAC_ADDRESS Set the default gateway Set a sta-c route Change the device MAC address and many other func-ons for managing arp cache, policy rou-ng, mul-ple rou-ng tables, tunnels, mul-cast addresses, IPsec policy, etc

16 Simplest Scenario VM1 eth0 eth0 VM / / 24

17 Basic Rou-ng eth0 VM3 eth / / 16 VM1 eth / 24 eth0 VM / 16

18 Outline Linux the Survivor Kit Netkit The poor man's system to experiment computer networking IpRoute2 show / manipulate rou-ng, devices, policy rou-ng and tunnels Wireshark network analyzer and sniffer

19 Wireshark: the network analyzer Wireshark is the world's foremost network protocol analyzer, and is the de facto (and ojen de jure) standard across many industries and educa-onal ins-tu-ons. Wireshark development thrives thanks to the contribu-ons of networking experts across the globe. It is the con-nua-on of a project that started in 1998 (Ethereal). Ethereal logo Wireshark screeshot

20 Wireshark features * Deep inspec-on of hundreds of protocols, with more being added all the -me * Live capture and offline analysis * Standard three pane packet browser * Mul- plaorm: Runs on Windows, Linux, OS X, Solaris, FreeBSD, NetBSD, and many others * Captured network data can be browsed via a GUI, or via the TTY mode TShark u-lity * The most powerful display filters in the industry * Rich VoIP analysis * Read/write many different capture file formats * Capture files compressed with gzip can be decompressed on the fly * Live data can be read from Ethernet, IEEE , PPP/HDLC, ATM, Bluetooth, USB,,Token Ring, Frame Relay, FDDI, and others (depending on your plarom) * Decryp-on support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2 (having the keys ) * Coloring rules can be applied to the packet list for quick, intui-ve analysis * Output can be exported to XML, PostScript, CSV, or plain text and now, let s have fun!!!

21 Sekng up a TAP interface VM1 eth0 tap eth0 VM / / 24 nk_tap_something Host Machine / 24

22 Sta-c rou-ng scenario with a TAP interface VM /24 eth0 eth1 tap eth / /24 VM3 eth /24 VM1 eth / / /24 eth0 VM4 nk_tap_something Host Machine /0