ping:
It
is
a
computer
network
administration
utility
used
to
test
the
reachability
of
a
host
on
an
internet
protocol
(IP)
network
and
to
measure
the
round-trip-time
for
messages
sent
from
the
originating
host
to
a
distination
computer.
“ping”
operates
by
sending
internet
control
message
protocol
(ICMP)
echo-request
pachets
to
the
target
host
and
waiting
for
an
ICMP
response.
It
measures:-
- Time from transmission to reception (round-trip-time)
- Records any packet lost
- Response any packet received (i.e. Records of packet transmitted and packet received)
- Maximum, minimum and mean round-trip-time
- Standard deviation of the mean
For
the
following
hosts,
send
10
packets,
each
with
a
length
of
56
data
bytes.
The
hosts
are
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
ping
-c
10
www.iitg.ernet.in
PING
www.iitg.ernet.in
(202.141.80.6):
56
data
bytes
64
bytes
from
202.141.80.6:
icmp_seq=0
ttl=63
time=0.899
ms
64
bytes
from
202.141.80.6:
icmp_seq=1
ttl=63
time=3.091
ms
64
bytes
from
202.141.80.6:
icmp_seq=2
ttl=63
time=2.382
ms
64
bytes
from
202.141.80.6:
icmp_seq=3
ttl=63
time=0.791
ms
64
bytes
from
202.141.80.6:
icmp_seq=4
ttl=63
time=0.571
ms
64
bytes
from
202.141.80.6:
icmp_seq=5
ttl=63
time=3.921
ms
64
bytes
from
202.141.80.6:
icmp_seq=6
ttl=63
time=0.706
ms
64
bytes
from
202.141.80.6:
icmp_seq=7
ttl=63
time=1.021
ms
64
bytes
from
202.141.80.6:
icmp_seq=8
ttl=63
time=4.487
ms
64
bytes
from
202.141.80.6:
icmp_seq=9
ttl=63
time=0.740
ms
---
www.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.571/1.861/4.487/1.413
ms
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
Observation:
- packet loss = 0%
- packets transmitted =10
- packets received = 10
- minimum round-trip time = 0.571 ms
- mean round-trip time = 1.861 ms
- maximum round-trip time = 4.487 ms
- standard deviation of mean = 1.413 ms
- jatinga.iitg.ernet.in
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
ping
-c
10
jatinga.iitg.ernet.in
PING
jatinga.iitg.ernet.in
(202.141.81.145):
56
data
bytes
64
bytes
from
202.141.81.145:
icmp_seq=0
ttl=63
time=3.164
ms
64
bytes
from
202.141.81.145:
icmp_seq=1
ttl=63
time=0.611
ms
64
bytes
from
202.141.81.145:
icmp_seq=2
ttl=63
time=0.567
ms
64
bytes
from
202.141.81.145:
icmp_seq=3
ttl=63
time=0.590
ms
64
bytes
from
202.141.81.145:
icmp_seq=4
ttl=63
time=0.520
ms
64
bytes
from
202.141.81.145:
icmp_seq=5
ttl=63
time=0.691
ms
64
bytes
from
202.141.81.145:
icmp_seq=6
ttl=63
time=0.532
ms
64
bytes
from
202.141.81.145:
icmp_seq=7
ttl=63
time=0.544
ms
64
bytes
from
202.141.81.145:
icmp_seq=8
ttl=63
time=0.907
ms
64
bytes
from
202.141.81.145:
icmp_seq=9
ttl=63
time=0.521
ms
---
jatinga.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.520/0.865/3.164/0.774
ms
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
Observation:
- packet loss = 0%
- packets transmitted =10
- packets received = 10
- minimum round-trip time = 0.520 ms
- mean round-trip time = 0.865 ms
- maximum round-trip time = 3.164 ms
- standard deviation of mean = 0.774 ms
- 10.10.0.254
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
ping
-c
10
10.10.0.254
PING
10.10.0.254
(10.10.0.254):
56
data
bytes
64
bytes
from
10.10.0.254:
icmp_seq=0
ttl=64
time=1.123
ms
64
bytes
from
10.10.0.254:
icmp_seq=1
ttl=64
time=4.456
ms
64
bytes
from
10.10.0.254:
icmp_seq=2
ttl=64
time=0.746
ms
64
bytes
from
10.10.0.254:
icmp_seq=3
ttl=64
time=0.762
ms
64
bytes
from
10.10.0.254:
icmp_seq=4
ttl=64
time=2.113
ms
64
bytes
from
10.10.0.254:
icmp_seq=5
ttl=64
time=0.812
ms
64
bytes
from
10.10.0.254:
icmp_seq=6
ttl=64
time=0.769
ms
64
bytes
from
10.10.0.254:
icmp_seq=7
ttl=64
time=0.737
ms
64
bytes
from
10.10.0.254:
icmp_seq=8
ttl=64
time=0.690
ms
64
bytes
from
10.10.0.254:
icmp_seq=9
ttl=64
time=3.024
ms
---
10.10.0.254
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.690/1.523/4.456/1.222
ms
root@asbidyarthy-Studio-1555:/home/asbidyarthy#
Observation:
- packet loss = 0%
- packets transmitted =10
- packets received = 10
- minimum round-trip time = 0.690 ms
- mean round-trip time = 1.523 ms
- maximum round-trip time = 4.456 ms
- standard deviation of mean = 1.222 ms
Q1.
You
may
find
that
the
packet
responses
are
64
bytes
instead
of
56
bytes.
Find
out
the
reason
for
this.
Answer:
when
we
use
ping
www.example.com,
The
default
number
of
data
bytes
to
be
sent
is
56
bytes,
which
translates
into
64
ICMP
data
bytes
when
combined
with
the
8
bytes
of
ICMP
header
data.
Since
“ping”
operates
by
sending
internet
control
message
protocol
(ICMP)
echo-request
packets
to
the
target
host
and
waiting
for
an
ICMP
response.
Echo-request
message
takes
additional
8
bytes
of
ICMP
header
data
to
reach
distination
host
and
echo-reply
takes
additional
0
byte
of
ICMP
header
data
to
reach
source
host.
When
echo-request
message
is
requested
from
source
to
distination
and
echo-reply
message
is
replied
by
distination,
in
this
case
for
echo-reply
message
source
becomes
distination
and
distination
becomes
source
host.
The ICMP header is composed of a:
- Type
- Code
- Header checksum
- ID
- Sequence
Below, is the ICMP protocol structure. This snapshot can be seen in wireshark. Wireshark is a network packet analyzer. A network packet analyzer will try to capture network packets and tries to display that packet data as detailed as possible.
Below, you can find some ICMP types.
|
Type |
Description |
|
|
|
|
0 |
Echo reply |
|
3 |
Destination unreachable |
|
4 |
Source quench |
|
5 |
Redirect |
|
8 |
Echo request |
|
9 |
Router advertisement |
|
10 |
Router solicitation |
|
11 |
Time exceeded |
|
12 |
Parameter problem |
|
13 |
Timestamp request |
|
14 |
Timestamp reply |
|
15 |
Information request |
|
16 |
Information reply |
|
17 |
Address mask request |
|
18 |
Address mask reply |
|
30 |
Traceroute |
Q2.
Explain
the
differences
in
minimum
round
trip
time
of
each
of
these
hosts.
Answer:
---
www.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.571/1.861/4.487/1.413
ms
---
jatinga.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.520/0.865/3.164/0.774
ms
---
10.10.0.254
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
0.690/1.523/4.456/1.222
ms
The
further
the
destination
is
from
IIT,
the
longer
the
propagation
time.
If
the
distance
of
the
distination
host
willl
increase,
will
also
increase
minimum
round-trip
time.
Www.iitg.ernet.in
and
jatinga.iitg.ernet.in
both
are
on
IIT
campus,
hence
are
oly
a
few
milliseconds
away,
therefore
the
minimum
round-trip
time
is
very
less
i.e.
0.571
and
0.520
ms
respectively,
while
10.10.0.254
is
default
gateway
is
also
taking
very
less
minimum
round-trip
time
i.e.
0.690
ms
.
Q3.
Now
send
pings
with
128,
512,
and
1024
byte
packets
to
all
of
the
three
hosts
above.
Write
down
the
minimum,
average
and
maximum
round
trip
time.
Why
are
the
minimum
round-trip
times
to
the
same
hosts
different
when
using
128,
512,
and
1024
byte
packets?
128
bytes
data
packets
---
www.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
11.284/17.614/20.732/2.813
ms
---
jatinga.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
9.504/18.226/21.969/3.585
ms
---
10.10.0.254
ping
statistics
---
10
packets
transmitted,
9
packets
received,
10%
packet
loss
round-trip
min/avg/max/stddev
=
9.093/16.821/21.763/4.417
ms
512
bytes
data
packets
---
www.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
8.519/17.253/21.761/3.878
ms
---
jatinga.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
8
packets
received,
20%
packet
loss
round-trip
min/avg/max/stddev
=
16.707/20.074/22.493/2.243
ms
---
10.10.0.254
ping
statistics
---
10
packets
transmitted,
7
packets
received,
30%
packet
loss
round-trip
min/avg/max/stddev
=
9.210/17.971/22.274/4.404
ms
1024
bytes
data
packets
---
www.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
12.214/18.398/22.553/3.818
ms
---
jatinga.iitg.ernet.in
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
11.121/18.681/24.254/3.575
ms
---
10.10.0.254
ping
statistics
---
10
packets
transmitted,
10
packets
received,
0%
packet
loss
round-trip
min/avg/max/stddev
=
8.687/14.737/20.710/4.153
ms
Larger
packets
have
a
longer
transmission
delay,
since
the
sending
and
receiving
machines
must
spend
more
time
just
getting
the
packet
on
and
off
the
network.
The
time
it
takes
to
put
the
packet
onto
the
network
is
determined
by
the
bandwidth
and
the
amount
of
data
being
transmitted.
However,
the
transmission
delay
is
small
compared
to
the
latency
caused
by
the
propagation
delay.
Hence
the
amount
of
additional
time
for
larger
packets
is
small
compared
to
the
round
trip
time
for
small
packets.
Q4.
Note
that
you
can’t
ping
an
outside
host
from
inside
IITG
network.
Find
out
the
to
ping
following
hosts,
i)
www.berkeley.edu
ii)
www.kyoto-u.ac.jp
iii)
www.csail.mit.edu
iv)
www.iitg.ernet.in
Answer
all
the
questions
Q1-Q3
for
this
part.
Answer:
we
send
an
ICMP
Echo
request
from
my
IP
to
external
LAN's
IP- This routes by way of our router.
- Our network address translation (NAT) gateway inside our router rewrites the request to be from external LAN's IP (it's static IP address)
- Our router replies to the ICMP Echo request
- Since our
router
does not
support
ICMP
state, it
never
passes the
ECHO Reply
back to
us.
Q1.
You
may
find
that
the
packet
responses
are
64
bytes
instead
of
56
bytes.
Find
out
the
reason
for
this.
Answer:
Same
as
above
Q2.
Explain
the
differences
in
minimum
round
trip
time
of
each
of
these
hosts.
Answer:
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
88
|
|
|
|
received |
10
|
100%
|
|
avg |
92
|
|
|
|
lost |
0
|
0%
|
|
max |
99
|
|
(kyoto,
kyoto,
Japan)
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
174
|
|
|
|
received |
10
|
100%
|
|
avg |
175
|
|
|
|
lost |
0
|
0%
|
|
max |
185
|
|
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
45
|
|
|
|
received |
10
|
100%
|
|
avg |
45
|
|
|
|
lost |
0
|
0%
|
|
max |
45
|
|
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
300
|
|
|
|
received |
10
|
100%
|
|
avg |
300
|
|
|
|
lost |
0
|
0%
|
|
max |
301
|
|
city
name
is
Houston,
state
name
is
Texas,
country
name
is
United
states,
the
longer
the
propagation
time.If
the
distance
of
the
distination
host
willl
increase,
will
also
increase
minimum
round-trip
time.
Since
Distance
from
Houston
to
India>Kyoto>
Berkeley>
Cambridge
therefore
minimum
round-trip
time
of
www.iitg.ernet.in
>www.kyoto-u.ac.jp
>www.berkeley.edu
>www.csail.mit.edu
Q3.
Now
send
pings
with
128,
512,
and
1024
byte
packets
to
all
of
the
three
hosts
above.
Write
down
the
minimum,
average
and
maximum
round
trip
time.
Why
are
the
minimum
round-trip
times
to
the
same
hosts
different
when
using
128,
512,
and
1024
byte
packets?
Answer:
128
bytes
data
packets
i)
www.berkeley.edu
ii)
www.kyoto-u.ac.jp
iii)
www.csail.mit.edu
- www.iitg.ernet.in
which
you have
provided to
ping
outside
network
hosts is
accepting
data
packets of
size less
than 100.
Data size must be a number from 0 to 100.
-- end --
Q5.
Send
pings to
the host
www.wits.ac.za
, and
www.microsoft.com
, for
some of
the hosts,
you may
not have
received
any
responses
for the
packets you
sent. What
are some
reasons as
to why
you might
have not
gotten a
response?
(Be sure
to check
the hosts
in a
web
browser.)
Answer:
IP
country
code:
ZA
IP
address
country:
South
Africa
IP
address
state:
Gauteng
IP
address
city:
Johannesburg
IP
address
latitude:
-26.2000
IP
address
longitude:
28.0833
ISP
of
this
IP
[?]:
University
of
the
Witwatersrand
Organization:
University
of
the
Witwatersrand
Local
time
in
South
Africa:
2011-12-31
21:08
Results
|
count
|
ttl (hops)
|
rtt (ms)
|
|
from
|
|
|
|
|
1
|
|
|
|
|
|
TimedOut |
|
|
2
|
|
|
|
|
|
TimedOut |
|
|
3
|
|
|
|
|
|
TimedOut |
|
|
4
|
|
|
|
|
|
TimedOut |
|
|
5
|
|
|
|
|
|
TimedOut |
|
|
6
|
|
|
|
|
|
TimedOut |
|
|
7
|
|
|
|
|
|
TimedOut |
|
|
8
|
|
|
|
|
|
TimedOut |
|
|
9
|
|
|
|
|
|
TimedOut |
|
|
10
|
|
|
|
|
|
TimedOut |
|
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
-
|
|
|
|
received |
0
|
0%
|
|
avg |
-
|
|
|
|
lost |
10
|
100%
|
|
max |
-
|
|
IP
country
code:
US
IP
address
country:
United
States
IP
address
state:
n/a
IP
address
city:
n/a
Results
|
count
|
ttl (hops)
|
rtt (ms)
|
|
from
|
|
|
|
|
1
|
|
|
|
|
|
TimedOut |
|
|
2
|
|
|
|
|
|
TimedOut |
|
|
3
|
|
|
|
|
|
TimedOut |
|
|
4
|
|
|
|
|
|
TimedOut |
|
|
5
|
|
|
|
|
|
TimedOut |
|
|
6
|
|
|
|
|
|
TimedOut |
|
|
7
|
|
|
|
|
|
TimedOut |
|
|
8
|
|
|
|
|
|
TimedOut |
|
|
9
|
|
|
|
|
|
TimedOut |
|
|
10
|
|
|
|
|
|
TimedOut |
|
Statistics
|
packets
|
sent |
10
|
|
times (ms)
|
min |
-
|
|
|
|
received |
0
|
0%
|
|
avg |
-
|
|
|
|
lost |
10
|
100%
|
|
max |
-
|
|
Neither of these machines send back any ping responses. A few possible reasons:
Saving of resources: The sites might be trying to minimize the number of services on its web site so that the system can focus on serving web requests.
Security: By providing fewer services, fewer security "holes" are likely to exist. People have been known to use ping to send very large packets to hosts. These packets cause the servers buffers to overflow and crash the system.
Firewall: The www.microsoft.com machine could be hidden behind a firewall which only allows http requests to pass. Hence ICMP packets never make it to www.microsoft.com.
Crash: The system on the other end might have crashed.
Temporary Congestion: The network may be dropping packets because of congestion.
Network failure: The network connection to or from a host may have failed.
Hacked Machine: A machine was modified to behave by dropping packets.
Because both of these hosts run a functioning web server, the true reason for not receiving responses is more likely some of the first three reasons than the last four.
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