Which first 8 bytes of the IP datagram are included in ICMP message?












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The definition of ICMP message says that it has a type, a code and the first 8 bytes of IP datagram causing error.



Question: Which first 8 bytes of IP datagram are included in the ICMP datagram?



My understanding: The portion marked by the red box in the figure below.



enter image description here










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    1














    The definition of ICMP message says that it has a type, a code and the first 8 bytes of IP datagram causing error.



    Question: Which first 8 bytes of IP datagram are included in the ICMP datagram?



    My understanding: The portion marked by the red box in the figure below.



    enter image description here










    share|improve this question

























      1












      1








      1







      The definition of ICMP message says that it has a type, a code and the first 8 bytes of IP datagram causing error.



      Question: Which first 8 bytes of IP datagram are included in the ICMP datagram?



      My understanding: The portion marked by the red box in the figure below.



      enter image description here










      share|improve this question













      The definition of ICMP message says that it has a type, a code and the first 8 bytes of IP datagram causing error.



      Question: Which first 8 bytes of IP datagram are included in the ICMP datagram?



      My understanding: The portion marked by the red box in the figure below.



      enter image description here







      icmp






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      asked Dec 8 at 20:46









      Banghua Zhao

      237111




      237111






















          2 Answers
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          Well, the sender might like to know which ones of its packets the ICMP message refers to. For that, the entire IP header plus (at least) the first eight bytes of the IP payload are appended to the ICMP header for error messages.






          share|improve this answer































            0














            I am not sure what definition you are referring to (source?), but it probably meant a 8 bit.



            An ICMP packet is 8 bytes total[1], the first 16 bits are type and code bytes(eight bits in a byte); the type byte is given a number from 0 to 255[2], a different number representing a different type of sub-code.



            As Zac67 stated the sender usually likes to know where the ICMP packet comes from, so it encapsulates it in an IP header, that IP header contains a field called 'protocol' when an ICMP packet is carried in the payload the protocol field is set[3] to 1 (0x01 in hex or 00000001 in binary), the protocol field is also bits (1 byte) long.



            Below is some useful resources and sources.
            Hope this helps.



            https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol



            http://slideplayer.com/slide/3602717/



            http://www.enterprisenetworkingplanet.com/netsp/article.php/3584166/Networking-101-Understanding-and-Using-ICMP.htm



            http://www.pearsonitcertification.com/articles/article.aspx?p=1804873



            [1] - http://www.keyboardbanger.com/wp-content/uploads/2015/07/ICMP-header.png



            [2] - https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol#Control_messages



            [3] - https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers






            share|improve this answer

















            • 2




              The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
              – Ron Maupin
              Dec 9 at 21:17











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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            3














            Well, the sender might like to know which ones of its packets the ICMP message refers to. For that, the entire IP header plus (at least) the first eight bytes of the IP payload are appended to the ICMP header for error messages.






            share|improve this answer




























              3














              Well, the sender might like to know which ones of its packets the ICMP message refers to. For that, the entire IP header plus (at least) the first eight bytes of the IP payload are appended to the ICMP header for error messages.






              share|improve this answer


























                3












                3








                3






                Well, the sender might like to know which ones of its packets the ICMP message refers to. For that, the entire IP header plus (at least) the first eight bytes of the IP payload are appended to the ICMP header for error messages.






                share|improve this answer














                Well, the sender might like to know which ones of its packets the ICMP message refers to. For that, the entire IP header plus (at least) the first eight bytes of the IP payload are appended to the ICMP header for error messages.







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Dec 9 at 21:26

























                answered Dec 8 at 21:02









                Zac67

                26k21352




                26k21352























                    0














                    I am not sure what definition you are referring to (source?), but it probably meant a 8 bit.



                    An ICMP packet is 8 bytes total[1], the first 16 bits are type and code bytes(eight bits in a byte); the type byte is given a number from 0 to 255[2], a different number representing a different type of sub-code.



                    As Zac67 stated the sender usually likes to know where the ICMP packet comes from, so it encapsulates it in an IP header, that IP header contains a field called 'protocol' when an ICMP packet is carried in the payload the protocol field is set[3] to 1 (0x01 in hex or 00000001 in binary), the protocol field is also bits (1 byte) long.



                    Below is some useful resources and sources.
                    Hope this helps.



                    https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol



                    http://slideplayer.com/slide/3602717/



                    http://www.enterprisenetworkingplanet.com/netsp/article.php/3584166/Networking-101-Understanding-and-Using-ICMP.htm



                    http://www.pearsonitcertification.com/articles/article.aspx?p=1804873



                    [1] - http://www.keyboardbanger.com/wp-content/uploads/2015/07/ICMP-header.png



                    [2] - https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol#Control_messages



                    [3] - https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers






                    share|improve this answer

















                    • 2




                      The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                      – Ron Maupin
                      Dec 9 at 21:17
















                    0














                    I am not sure what definition you are referring to (source?), but it probably meant a 8 bit.



                    An ICMP packet is 8 bytes total[1], the first 16 bits are type and code bytes(eight bits in a byte); the type byte is given a number from 0 to 255[2], a different number representing a different type of sub-code.



                    As Zac67 stated the sender usually likes to know where the ICMP packet comes from, so it encapsulates it in an IP header, that IP header contains a field called 'protocol' when an ICMP packet is carried in the payload the protocol field is set[3] to 1 (0x01 in hex or 00000001 in binary), the protocol field is also bits (1 byte) long.



                    Below is some useful resources and sources.
                    Hope this helps.



                    https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol



                    http://slideplayer.com/slide/3602717/



                    http://www.enterprisenetworkingplanet.com/netsp/article.php/3584166/Networking-101-Understanding-and-Using-ICMP.htm



                    http://www.pearsonitcertification.com/articles/article.aspx?p=1804873



                    [1] - http://www.keyboardbanger.com/wp-content/uploads/2015/07/ICMP-header.png



                    [2] - https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol#Control_messages



                    [3] - https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers






                    share|improve this answer

















                    • 2




                      The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                      – Ron Maupin
                      Dec 9 at 21:17














                    0












                    0








                    0






                    I am not sure what definition you are referring to (source?), but it probably meant a 8 bit.



                    An ICMP packet is 8 bytes total[1], the first 16 bits are type and code bytes(eight bits in a byte); the type byte is given a number from 0 to 255[2], a different number representing a different type of sub-code.



                    As Zac67 stated the sender usually likes to know where the ICMP packet comes from, so it encapsulates it in an IP header, that IP header contains a field called 'protocol' when an ICMP packet is carried in the payload the protocol field is set[3] to 1 (0x01 in hex or 00000001 in binary), the protocol field is also bits (1 byte) long.



                    Below is some useful resources and sources.
                    Hope this helps.



                    https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol



                    http://slideplayer.com/slide/3602717/



                    http://www.enterprisenetworkingplanet.com/netsp/article.php/3584166/Networking-101-Understanding-and-Using-ICMP.htm



                    http://www.pearsonitcertification.com/articles/article.aspx?p=1804873



                    [1] - http://www.keyboardbanger.com/wp-content/uploads/2015/07/ICMP-header.png



                    [2] - https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol#Control_messages



                    [3] - https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers






                    share|improve this answer












                    I am not sure what definition you are referring to (source?), but it probably meant a 8 bit.



                    An ICMP packet is 8 bytes total[1], the first 16 bits are type and code bytes(eight bits in a byte); the type byte is given a number from 0 to 255[2], a different number representing a different type of sub-code.



                    As Zac67 stated the sender usually likes to know where the ICMP packet comes from, so it encapsulates it in an IP header, that IP header contains a field called 'protocol' when an ICMP packet is carried in the payload the protocol field is set[3] to 1 (0x01 in hex or 00000001 in binary), the protocol field is also bits (1 byte) long.



                    Below is some useful resources and sources.
                    Hope this helps.



                    https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol



                    http://slideplayer.com/slide/3602717/



                    http://www.enterprisenetworkingplanet.com/netsp/article.php/3584166/Networking-101-Understanding-and-Using-ICMP.htm



                    http://www.pearsonitcertification.com/articles/article.aspx?p=1804873



                    [1] - http://www.keyboardbanger.com/wp-content/uploads/2015/07/ICMP-header.png



                    [2] - https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol#Control_messages



                    [3] - https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers







                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered Dec 9 at 21:09









                    Xuebit

                    1




                    1








                    • 2




                      The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                      – Ron Maupin
                      Dec 9 at 21:17














                    • 2




                      The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                      – Ron Maupin
                      Dec 9 at 21:17








                    2




                    2




                    The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                    – Ron Maupin
                    Dec 9 at 21:17




                    The real definition of ICMP is RFC 792, Internet Control Message Protocol. An ICMP message can certainly be longer than eight total bytes. In fact, it will include the IP header (20 bytes for IPv4) and the first 64 bits (eight bytes) of the IP payload: "The internet header plus the first 64 bits of the original datagram's data." That is enough to include the source and destination addresses of protocols like TCP or UDP.
                    – Ron Maupin
                    Dec 9 at 21:17


















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