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Assignment 6 Implement ping using raw sockets
Assignment 6
Implement ping using raw sockets
Introduction:
The ping command got its name from the sound sonar makes when it "sees" something. In
sonar, you send out a signal and measure the time it takes to get there. The ping command
does the same thing. This tells if a computer or device is out there or not, which is the
purpose of the command. I t is basically a network diagnostic tool that’s used to check if a host
in a network is alive and responding. Ping uses ICMP messages. More particularly ICMP query
messages.
ICMP:
ICMP (Internet Control Message Protocol) is a companion to the IP protocol. It compensates the
IP protocol in error reporting since IP protocol doesn’t have an error reporting method in place.
ICMP only reports errors and expects higher layers of the TCP/IP architecture model to handle
and correct the errors.
ICMP has two types of messages error
reporting messages and query messages. Query
messages are generally used to diagnose network problems. There are two types of query
messages
1. Echorequest
message
2. Echoreply
message
Generic composition of an ICMP 32byte
packet:
● IP Header: protocol set to 1 (ICMP) and Type of Service set to 0.
● ICMP Header:
● Type of ICMP message (8 bits)
● Code (8 bits)
● Checksum (16 bits), calculated with the ICMP part of the packet (the IP
header is not used). It is the 16bit
one's complement of the one's
complement sum of the ICMP message starting with the Type field
● Header Data (32 bits) field, which in this case (ICMP echo request and
replies), will be composed of identifier (16 bits) and sequence number (16
bits).
● ICMP Payload: p ayload for the different kind of answers; can be an arbitrary length,
left to implementation detail. However, the packet including IP and ICMP headers
must be less than the maximum transmission unit of the network or risk being
fragmented
The ping process:
● The source sends an ICMP echorequest
message to the destination.
● The ping program sets a sequence identifier which gets incremented with each
echorequest
message. It also sets a TTL (Timetolive)
period .
● Ping also inserts the sending time in the data section of the message.
● If the host is alive and responding, it sends an ICMP echoreply
message back to the
source.
● Ping notes the time of the arrival of the response message, uses the sending time in the
message part and calculates the Roundtrip
time
● It then increments the sequence identifier (as said above) and sends a new echorequest
message. This goes on for the number of ping requests set by the user or the program is
terminated.
The whole of the data is calculated to summarize the percentage of packet loss and other such
information and the summarized data is then displayed, showing the number of packets
transmitted, received, percentage of packet loss, total time taken, the minimum, average and
maximum roundtrip
time. This ofcourse, is in addition to the data displayed live when the
program is running.
Sample:
ping www.google.co.in
PING www.google.co.in (74.125.68.94) 56(84) bytes of data.
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=1 ttl=43 time=98.8 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=2 ttl=43 time=174 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=3 ttl=43 time=131 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=4 ttl=43 time=98.5 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=5 ttl=43 time=107 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=6 ttl=43 time=101 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=7 ttl=43 time=100 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=8 ttl=43 time=108 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=9 ttl=43 time=101 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=10 ttl=43 time=105 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=11 ttl=43 time=102 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=12 ttl=43 time=122 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=13 ttl=43 time=106 ms
www.
google.co.in ping statistics 13
packets transmitted, 13 received, 0% packet loss, time 12015ms
rtt min/avg/max/mdev = 98.593/112.265/174.998/20.325 ms
Output Explained:
1. PING www.google.co.in (74.125.68.94): Ping only knows how to communicate with IP
addresses, so the first thing it did when asked to ping “google.co.in” was to look up the
corresponding IP address. This is one of the quickest ways to determine the IP address
associated with a domain. Also, if this lookup
fails, we know there’s a typo in the domain
name, or the domain name lookup
(DNS) is failing for some reason.
2. 64 bytes from scinf94.1e100.
net (74.125.68.94): This tells you that the remote server
at that IP address replied. What that means, though, is that the entire route across the
internet, from your machine through routers and switches and networking equipment and
whatever else, worked, as did the return path carrying the server’s reply. If this fails,
(“timed out”) then something along the connection between you and the server might be
broken, the server might be offline, or the server might not even exist. It’s also possible
the server is explicitly configured not to respond to ping requests.
3. time=98.8 ms: This is the round trip time: the time between sending “Are you there?” and
receiving “Yes I am!”. In this case, it took 98.8 milliseconds. Since the ping is repeated
several times, you can see that this time is fairly consistent, which is good. The time
varies depending on many factors, including how close you are to the remote server, how
many routers and other networking equipment are between you and that server, and
more.
4. 13 packets transmitted, 13 received: One of the things TCP/IP is designed to deal with
is packet loss. Ideally, every packet you send should get to where it’s going, but for
various reasons, that doesn’t always happen. As long as the packets can get there after
a retry or two, in normal usage you’d never notice. Ping sends multiple packets and
reports specifically on the success rate, so you can see if a particular connection is prone
to packet loss.
5. rtt min/avg/max/mdev: While on average the same kind of packet sent to the same
destination should take roughly the same amount of time, that’s also not always the case.
Some packets take longer than others, for reasons as diverse as the equipment involved
and paths followed. Ping reports these statistics so you can see if a particular connection
is prone to this type of problem. The information provided here are, minimum round trip
time (rtt), maximum rtt, average rtt and mean deviation.
Objective:
Implement a standard p ing application which uses raw sockets. The output should be similar as
shown in the sample.
Implement ping using raw sockets
Introduction:
The ping command got its name from the sound sonar makes when it "sees" something. In
sonar, you send out a signal and measure the time it takes to get there. The ping command
does the same thing. This tells if a computer or device is out there or not, which is the
purpose of the command. I t is basically a network diagnostic tool that’s used to check if a host
in a network is alive and responding. Ping uses ICMP messages. More particularly ICMP query
messages.
ICMP:
ICMP (Internet Control Message Protocol) is a companion to the IP protocol. It compensates the
IP protocol in error reporting since IP protocol doesn’t have an error reporting method in place.
ICMP only reports errors and expects higher layers of the TCP/IP architecture model to handle
and correct the errors.
ICMP has two types of messages error
reporting messages and query messages. Query
messages are generally used to diagnose network problems. There are two types of query
messages
1. Echorequest
message
2. Echoreply
message
Generic composition of an ICMP 32byte
packet:
● IP Header: protocol set to 1 (ICMP) and Type of Service set to 0.
● ICMP Header:
● Type of ICMP message (8 bits)
● Code (8 bits)
● Checksum (16 bits), calculated with the ICMP part of the packet (the IP
header is not used). It is the 16bit
one's complement of the one's
complement sum of the ICMP message starting with the Type field
● Header Data (32 bits) field, which in this case (ICMP echo request and
replies), will be composed of identifier (16 bits) and sequence number (16
bits).
● ICMP Payload: p ayload for the different kind of answers; can be an arbitrary length,
left to implementation detail. However, the packet including IP and ICMP headers
must be less than the maximum transmission unit of the network or risk being
fragmented
The ping process:
● The source sends an ICMP echorequest
message to the destination.
● The ping program sets a sequence identifier which gets incremented with each
echorequest
message. It also sets a TTL (Timetolive)
period .
● Ping also inserts the sending time in the data section of the message.
● If the host is alive and responding, it sends an ICMP echoreply
message back to the
source.
● Ping notes the time of the arrival of the response message, uses the sending time in the
message part and calculates the Roundtrip
time
● It then increments the sequence identifier (as said above) and sends a new echorequest
message. This goes on for the number of ping requests set by the user or the program is
terminated.
The whole of the data is calculated to summarize the percentage of packet loss and other such
information and the summarized data is then displayed, showing the number of packets
transmitted, received, percentage of packet loss, total time taken, the minimum, average and
maximum roundtrip
time. This ofcourse, is in addition to the data displayed live when the
program is running.
Sample:
ping www.google.co.in
PING www.google.co.in (74.125.68.94) 56(84) bytes of data.
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=1 ttl=43 time=98.8 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=2 ttl=43 time=174 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=3 ttl=43 time=131 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=4 ttl=43 time=98.5 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=5 ttl=43 time=107 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=6 ttl=43 time=101 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=7 ttl=43 time=100 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=8 ttl=43 time=108 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=9 ttl=43 time=101 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=10 ttl=43 time=105 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=11 ttl=43 time=102 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=12 ttl=43 time=122 ms
64 bytes from scinf94.1e100.
net (74.125.68.94): icmp_seq=13 ttl=43 time=106 ms
www.
google.co.in ping statistics 13
packets transmitted, 13 received, 0% packet loss, time 12015ms
rtt min/avg/max/mdev = 98.593/112.265/174.998/20.325 ms
Output Explained:
1. PING www.google.co.in (74.125.68.94): Ping only knows how to communicate with IP
addresses, so the first thing it did when asked to ping “google.co.in” was to look up the
corresponding IP address. This is one of the quickest ways to determine the IP address
associated with a domain. Also, if this lookup
fails, we know there’s a typo in the domain
name, or the domain name lookup
(DNS) is failing for some reason.
2. 64 bytes from scinf94.1e100.
net (74.125.68.94): This tells you that the remote server
at that IP address replied. What that means, though, is that the entire route across the
internet, from your machine through routers and switches and networking equipment and
whatever else, worked, as did the return path carrying the server’s reply. If this fails,
(“timed out”) then something along the connection between you and the server might be
broken, the server might be offline, or the server might not even exist. It’s also possible
the server is explicitly configured not to respond to ping requests.
3. time=98.8 ms: This is the round trip time: the time between sending “Are you there?” and
receiving “Yes I am!”. In this case, it took 98.8 milliseconds. Since the ping is repeated
several times, you can see that this time is fairly consistent, which is good. The time
varies depending on many factors, including how close you are to the remote server, how
many routers and other networking equipment are between you and that server, and
more.
4. 13 packets transmitted, 13 received: One of the things TCP/IP is designed to deal with
is packet loss. Ideally, every packet you send should get to where it’s going, but for
various reasons, that doesn’t always happen. As long as the packets can get there after
a retry or two, in normal usage you’d never notice. Ping sends multiple packets and
reports specifically on the success rate, so you can see if a particular connection is prone
to packet loss.
5. rtt min/avg/max/mdev: While on average the same kind of packet sent to the same
destination should take roughly the same amount of time, that’s also not always the case.
Some packets take longer than others, for reasons as diverse as the equipment involved
and paths followed. Ping reports these statistics so you can see if a particular connection
is prone to this type of problem. The information provided here are, minimum round trip
time (rtt), maximum rtt, average rtt and mean deviation.
Objective:
Implement a standard p ing application which uses raw sockets. The output should be similar as
shown in the sample.
1 file (129.6KB)
