By B.A.KhivsaraAssistant Professor

Computer DepartmentSNJB’s KBJ COE, Chandwad

Networking commands

Trace Route In detail

Python Program for traceroute

Networking commands

Trace Route In detail

Python Program for traceroute

finger : Display information about the system users. Ex: finger Deepak

ftp : File transfer program. (ftp <remote system name/ip)

ifconfig :Configure a network interface.Ex: ifconfig eth0 address 172.31.2.2 netmask255.255.0.0

ifdown : Shutdown a network interface. Ex: ifdown eth0

ifup : Brings a network interface up. Ex: ifupeth0

netconfig : step by step network configuration program.

netstat : Displays information about the systems network connections, including port connections, routing tables, and more. The command "netstar -r" will display the routing table. (netsat –rn)

nslookup : Used to query DNS servers for information about hosts.

ping : Send ICMP ECHO_REQUEST packets to network hosts. (ping <remote-host-name/ip)

showmount : Show mount information for an NFS server.

ssh : Secure Login (ssh <remote system name/ip>)

tcpdump : Dump traffic on a network. Prints out headers of packets that match the boolean expression. (tcpdump eth0)

telnet :setting up a remote login.

(telnet <remote system name/ip>)

traceroute : Print the route that packets take

to the specified network host.

(traceroute <remote system name/ip>)

route Show or manipulate the IP routing

table. (route, route add, route del)

Networking commands

Trace Route In detail

Python Program for traceroute

Tool used to trace path from source to destination host.

Most traceroute programs, send UDP packets (User Datagram Protocol).

Micrososft tracert sends ICMP echo request (ping) packets.

Unix: traceroute

Cisco IOS: traceroute (trace)

DOS: tracert

Transmits packets with small Time-To-Live (TTL) values.◦ First packets have TTL = 1

◦ Second have TTL = 2

◦ Third have TTL = 3

◦ etc.

TTL

Generates messages from each router used along the path.

Every router that handles a packet subtracts one from the packet's TTL.

If the TTL reaches zero, the packet has expiredand is discarded.

At that point, most routers send an ICMP Time Exceeded message back to the sender -traceroute uses this message.

A TTL value of one should produce a message from the first router; two from the second; etc.

Sender Target

TTL = 1 TTL = 2 TTL = 3 TTL = 4

Traceroute returns these IP addresses

& hostnames (via reverse lookup)

traceroute [ -dFInrvx ] [ -f first_ttl ]

[ -g gateway ] [ -i iface ] [ -m max_ttl ]

[ -p port ] [ -q nqueries ] [ -s src_addr ]

[ -t tos ] [ -w waittime ] [ -z pausemsecs ]

host [ packetlen]

-f Set the initial time-to-live used in the first outgoing probe packet.

-F Set the "don't fragment" bit.

-d Enable socket level debugging.

-g Specify a loose source route gateway (8 maximum).

-i Specify a network interface to obtain the source IP address for

outgoing probe packets.

-I Use ICMP ECHO instead of UDP datagrams.

-m Set the max time-to-live (max number of hops) used in outgoing

probe packets. The default is 30 hops.

-n Print hop addresses numerically rather than symbolically and

numerically

traceroute nis.nsf.net.

traceroute to nis.nsf.net (35.1.1.48), 30 hops max,

38 byte packet

1 helios.ee.lbl.gov (128.3.112.1) 19 ms 19 ms 0 ms

2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39

ms 19 ms

3 128.32.197.4 (128.32.197.4) 40 ms 59 ms 59 ms

4 nic.merit.edu (35.1.1.48) 239 ms 239 ms 239 ms

Hop

Round trip time

Router

C:\WINDOWS>tracert www.husd.k12.ca.us

Tracing route to www.husd.k12.ca.us [206.110.193.5]

over a maximum of 30 hops:

1 1 ms 1 ms 1 ms 192.168.0.1

2 23 ms 32 ms 32 ms adsl-63-198-176-254.dsl.snfc21.pacbell.net [63.198.176.254]

3 20 ms 19 ms 21 ms core4-g3-0.snfc21.pbi.net [216.102.187.130]

4 20 ms 19 ms 19 ms ded2-fa12-0-0.snfc21.pbi.net [209.232.130.5]

5 25 ms 51 ms 21 ms vip-Alameda-Co.cust-rtr.pacbell.net [216.102.184.2]

6 44 ms 37 ms 43 ms 206.110.252.174

7 47 ms 40 ms 40 ms www.husd.k12.ca.us [206.110.193.5]

Trace complete.

Round trip timeHop Router

Networking commands

Trace Route In detail

Python Program for traceroute

import socket

def main(dest_name):

#Getting IP address from Host Name

dest_addr = socket.gethostbyname(dest_name)

port = 33434

max_hops = 30

#initializing receiver and sender packets

icmp = socket.getprotobyname('icmp')

udp = socket.getprotobyname('udp')

ttl = 1while True:

#sending UDP and Receiving ICMP packetsrecv_socket = socket.socket(socket.AF_INET,

socket.SOCK_RAW, icmp)

send_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, udp)

#setting sender packet TTL field to value of the ttlvariable.

send_socket.setsockopt(socket.SOL_IP,socket.IP_TTL,ttl)

recv_socket.bind(("", port))

# code to send pkt using send Socket

send_socket.sendto("",(dest_name,port))

curr_addr = None

curr_name = None

try:

#retrieving the router address from packet_, curr_addr = recv_socket.recvfrom(512)curr_addr = curr_addr[0]try:

#getting hostname of the retrieved addresscurr_name = socket.gethostbyaddr(curr_addr)[0]

except socket.error:curr_name = curr_addr

except socket.error:pass

finally:send_socket.close()recv_socket.close()

#Printing data in the terminal if curr_addr is not None: curr_host = "%s (%s)" % (curr_name, curr_addr) else: curr_host = "*" print "%d\t%s" % (ttl, curr_host)

ttl += 1 if curr_addr == dest_addr or ttl > max_hops: break

if __name__ == "__main__": main('www.google.com')