Network Utilities Are Software Utilities Designed to Analyze and Configure Various Aspects of Computer Networks

Aim of the seminar Network Tools • Finding out or set your own IP address. • Finding out the MAC address your own and MAC of your neighbors. • Finding out your DNS server. • Determination the IP address by domain name. • Verifying availability to the other side and displaying transmission speed for the simple „request–reply“ communication. • Finding out the entire routing path to the other side. • Searching for more detailed information for the given SLD (second level domain). • To open remote session on the servers akela.mendelu.cz and user.mendelu.cz . • To upload/download files to/from them. 1 What we already know Network nodes addressing – HW address (MAC address) is given to a network adapter when it is manufactured. It has 48 bites. Example: 00-10-5A-44-12-B5 (in hexadecimal notation)

0000 0000 0001 0000 0101 1100 0100 0100 0001 0010 1101 0101 – 48 bites (6x8) – Logical address (IP address) is configured manually by user (administrator) or automatically. IPv4 address has 32 bites. Example: 172.16.254.1

– Domain name is assigned within the DNS (Internet Domain name system). Example: akela.mendelu.cz IRC - Lecture 2 - Networking 2 What we already know Domain Name System (DNS) • The number of an IP address can be (and usually is) represented by a name or series of names called domain name • Domain name locates an organization or other entity on the Internet. For example, the domain name akela.mendelu.cz locates an Internet address for domain "mendelu.cz" and a particular host server named „akela" at Internet point (i.e. IP address) 195.178.72.100 • DNS namespace - All domain names binding to IP addresses create hierarchical administrative namespace supporting Internet Domain name system (DNS) • A DNS server is a computer registered to join the Domain Name System. DNS server runs special-purpose networking software, features a public IP address, and contains a database of network names and addresses for other Internet hosts. IRC - Lecture 2 - Networking 3 What we already know DNS Namespace

IRC - Lecture 2 - Networking 4 What we already know Principle of DNS • Domain names need to be converted to IP addresses as this is required by lower layer protocols. • The conversion of domain names to IP addresses is performed by implementing of DNS protocol. • DNS protocol implementation

• Since an implementation of the DNS protocol is built into every network application program, the conversion is fully transparent to end users.

IRC - Lecture 2 - Networking 5 Network Tools What are Network Tools ?? Network tools/Network utilities are software utilities designed to analyze and configure various aspects of computer networks.

6 Network Tools • Network utilities are available on the different network operating systems (for example on Linux, Microsoft Windows, OS X, …..) • Network utilities set/display configuration of computer network interfaces, enable connection the remote computer, upload/download files. • Network utilities check network connection, measure the network traffic performance, display network statistics, are useful for network troubleshooting. 7 Network Tools The most common tools found on most operating systems include: 1. ifconfig/ipconfig allows for network interface configuration. 2. ping checks connectivity to other side (reports packet loss and response time). 3. arp allows to view and modify the ARP table including IP and MAC addresses of network neighbors. 4. route displays an IP routing table. 5. traceroute/tracert shows the series of successive nodes a packet goes through en route to its destination on a network. 6. nslookup gives a query a DNS (Domain Name System) server for obtaining DNS information.

8 Network Tools Network

Domain „mendelu.cz“ Border router Border router WAN University LAN Router Router www.google.com

Google LAN Switch Switch akela.mendelu.cz Domain „google.com“

Classroom Classroom

9 Network Tools

• Connection to GNU/Linux server akela.mendelu.cz

1 2

10 Network Tools

my_login xxxxxxx

11 Network Tools TCP/IP interface configuration query - MAC (HW) address and IP address • Linux (akela.mendelu.cz) - /sbin/ifconfig

MAC address

IP address

12 Network Tools IP host reachability test – ping [hostname] Measuring the round-trip time for messages sent from the originating host to a destination computer. • Linux ping utility

Round-trip time

13 Network Tools MAC to IP address resolution - the „Net Neighbors“ MAC addresses finding • Linux arp utility - display the content of ARP cache (ARP table)

Neighbor name

Neighbor IP address

14 NetworkTools Display of Routing table • Linux utility route

15 NetworkTools • Linux utility netstat –r - displays network connections for the TCP Transmission Control Protocol (both incoming and outgoing)

16 Network Tools Diagnostic tool for displaying the route (path) and measuring transit delays of packets across an IP network. • Linux – traceroute [hostname]

17 Network Tools

• Open Command Prompt window on the local PC (OS Microsoft Windows 10) 3 1

18 Network Tools

• MS Windows – ipconfig/all

Host name

IP address

19 Network Tools

• Windows ping utility

Round-trip time

20 Network Tools • MS Windows – arp utility

Neighbor IP address

21 Network Tools

• MS Windows – tracert [hostname]

22 Network Tools • MS Windows – route print

23 Network Tools

• MS Windows - netstat -r

24 Network Tools • Query Internet name servers interactively or non- interactively (DNS lookup utility) – nslookup (Linux, MS Windows)

25 NetworkTools • Secure transfer file from/to a remote host (download/upload) – Linux – scp [[user@]host1:]file1 [[user@]host2:]file2 – MS Windows – winscp program • Logging to the remote host (open the remote session) – Linux – ssh [user@]hostname [command] – MS Windows – putty program

26 Network tools online http://www.ping.eu

• Online Ping • Traceroute • DNS lookup Basic Network tools • WHOIS • Port check • Reverse lookup • Proxy checker • Bandwidth meter • Network calculator Additional Network tools • Network mask calculator • Country by IP • Unit converter Tool for general purpose

27 Network tools online www.whois.com

• Domain name lookup service to search the whois database for domain name registration information. • WHOIS is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block, or an autonomous system, but is also used for a wider range of other information.

28 Network tools Schema

Neighbors IP and MAC address ?

29 Warriors of the Net https://www.youtube.com/watch?v=PBWhzz_Gn10