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Autores Olivier Bonaventure
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Category tags http

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Analysis of an HTTP packet trace


Questão 1: A simple HTTP trace

Network engineers often need to capture the packets that are exchanged over a network to debug various types of problems. Here is a simple packet trace

Open this packet trace in wireshark or use tcpdump on the command line determine which of the affirmations below are correct.

Questão 2: The HTTP trace
# Length Summary Status
0 20 bytes Transmission Control Protocol, Src Port: 44914, Dst Port: 80, Seq: 0, Len: 0
1 20 bytes Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 0, Ack: 1, Len: 0
2 20 bytes Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 1, Ack: 1, Len: 0
3 117 bytes Hypertext Transfer Protocol
4 20 bytes Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 1, Ack: 86, Len: 0
5 497 bytes Hypertext Transfer Protocol
6 20 bytes Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 86, Ack: 466, Len: 0
7 20 bytes Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 466, Ack: 86, Len: 0
8 20 bytes Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 86, Ack: 467, Len: 0
9 20 bytes Transmission Control Protocol, Src Port: 80, Dst Port: 44914, Seq: 0, Ack: 1, Len: 0
10 20 bytes Transmission Control Protocol, Src Port: 44914, Dst Port: 80, Seq: 1, Len: 0
11 20 bytes Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 467, Ack: 87, Len: 0

0000  af72005014178133  00000000a0007210  
0010  88c20000                            

0000  ¯r.P...3......r.
0010  .Â..            
  • Transmission Control Protocol, Src Port: 44914, Dst Port: 80, Seq: 0, Len: 0
    • Source Port: 44914
      • Destination Port: 80
        • TCP Segment Len: 0
          • Sequence number: 0 (relative sequence number)
            • Acknowledgment number: 0
              • 1010 .... = Header Length: 40 bytes (10)
                • Window size value: 29200
                  • Calculated window size: 29200
                    • Checksum: 0x88c2 [unverified]
                      • Urgent pointer: 0
                      0000  0050b03e63660de9  95fa02fda000fb04  
                      0010  ad8b0000                            

                      0000  .P°>cf.é.ú.ý..û.
                      0010  ....            
                      • Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 0, Ack: 1, Len: 0
                        • Source Port: 80
                          • Destination Port: 45118
                            • TCP Segment Len: 0
                              • Sequence number: 0 (relative sequence number)
                                • Acknowledgment number: 1 (relative ack number)
                                  • 1010 .... = Header Length: 40 bytes (10)
                                    • Window size value: 64260
                                      • Calculated window size: 64260
                                        • Checksum: 0xad8b [unverified]
                                          • Urgent pointer: 0
                                          0000  b03e005095fa02fd  63660dea800000e1  
                                          0010  d4b50000                            

                                          0000  °>.P.ú.ýcf.ê...á
                                          0010  Ôµ..            
                                          • Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 1, Ack: 1, Len: 0
                                            • Source Port: 45118
                                              • Destination Port: 80
                                                • TCP Segment Len: 0
                                                  • Sequence number: 1 (relative sequence number)
                                                    • Acknowledgment number: 1 (relative ack number)
                                                      • 1000 .... = Header Length: 32 bytes (8)
                                                        • Window size value: 225
                                                          • Calculated window size: 225
                                                            • Window size scaling factor: -1 (unknown)
                                                              • Checksum: 0xd4b5 [unverified]
                                                                • Urgent pointer: 0
                                                                0000  b03e005095fa02fd  63660dea800000e1  
                                                                0010  1190000000000000  0000000000000000  
                                                                0020  474554202f726f62  6f74732e74787420  
                                                                0030  485454502f312e30  0d0a486f73743a20  
                                                                0040  6e6768747470322e  6f72670d0a557365  
                                                                0050  722d4167656e743a  206375726c2f372e  
                                                                0060  35382e300d0a4163  636570743a202a2f  
                                                                0070  2a0d0a0d0a                          

                                                                0000  °>.P.ú.ýcf.ê...á
                                                                0010  ................
                                                                0020  GET /robots.txt
                                                                0030  HTTP/1.0..Host:
                                                                0040  nghttp2.org..Use
                                                                0050  r-Agent: curl/7.
                                                                0060  58.0..Accept: */
                                                                0070  *....           
                                                                • Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 1, Ack: 1, Len: 85
                                                                  • Source Port: 45118
                                                                    • Destination Port: 80
                                                                      • TCP Segment Len: 85
                                                                        • Sequence number: 1 (relative sequence number)
                                                                          • Acknowledgment number: 1 (relative ack number)
                                                                            • 1000 .... = Header Length: 32 bytes (8)
                                                                              • Window size value: 225
                                                                                • Calculated window size: 225
                                                                                  • Window size scaling factor: -1 (unknown)
                                                                                    • Checksum: 0x1190 [unverified]
                                                                                      • Urgent pointer: 0
                                                                                        • TCP payload (85 bytes)
                                                                                        • Hypertext Transfer Protocol
                                                                                          • GET /robots.txt HTTP/1.0\r\n
                                                                                            • Request Method: GET
                                                                                              • Request URI: /robots.txt
                                                                                                • Request Version: HTTP/1.0
                                                                                                • Host: nghttp2.org\r\n
                                                                                                  • User-Agent: curl/7.58.0\r\n
                                                                                                    • Accept: */*\r\n
                                                                                                      • \r\n
                                                                                                      0000  0050b03e63660dea  95fa03528000007e  
                                                                                                      0010  d3d60000                            

                                                                                                      0000  .P°>cf.ê.ú.R...~
                                                                                                      0010  ÓÖ..            
                                                                                                      • Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 1, Ack: 86, Len: 0
                                                                                                        • Source Port: 80
                                                                                                          • Destination Port: 45118
                                                                                                            • TCP Segment Len: 0
                                                                                                              • Sequence number: 1 (relative sequence number)
                                                                                                                • Acknowledgment number: 86 (relative ack number)
                                                                                                                  • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                    • Window size value: 126
                                                                                                                      • Calculated window size: 64512
                                                                                                                        • Window size scaling factor: 512
                                                                                                                          • Checksum: 0xd3d6 [unverified]
                                                                                                                            • Urgent pointer: 0
                                                                                                                            0000  0050b03e63660dea  95fa03528000007e  
                                                                                                                            0010  505e000000000000  0000000000000000  
                                                                                                                            0020  485454502f312e30  20323030204f4b0d  
                                                                                                                            0030  0a446174653a2053  61742c203236204f  
                                                                                                                            0040  6374203230313920  32313a30373a3332  
                                                                                                                            0050  20474d540d0a436f  6e74656e742d5479  
                                                                                                                            0060  70653a2074657874  2f706c61696e0d0a  
                                                                                                                            0070  4c6173742d4d6f64  69666965643a204d  
                                                                                                                            0080  6f6e2c2031392041  7567203230313920  
                                                                                                                            0090  31333a32303a3336  20474d540d0a4574  
                                                                                                                            00A0  61673a2022356435  61613232342d3365  
                                                                                                                            00B0  220d0a4163636570  742d52616e676573  
                                                                                                                            00C0  3a2062797465730d  0a436f6e74656e74  
                                                                                                                            00D0  2d4c656e6774683a  2036320d0a582d42  
                                                                                                                            00E0  61636b656e642d48  65616465722d5274  
                                                                                                                            00F0  743a20302e303031  3331350d0a436f6e  
                                                                                                                            0100  6e656374696f6e3a  20636c6f73650d0a  
                                                                                                                            0110  5365727665723a20  6e6768747470780d  
                                                                                                                            0120  0a5669613a203220  6e6768747470780d  
                                                                                                                            0130  0a616c742d737663  3a2068332d32333d  
                                                                                                                            0140  223a34343333223b  206d613d33363030  
                                                                                                                            0150  0d0a782d6672616d  652d6f7074696f6e  
                                                                                                                            0160  733a2053414d454f  524947494e0d0a78  
                                                                                                                            0170  2d7873732d70726f  74656374696f6e3a  
                                                                                                                            0180  20313b206d6f6465  3d626c6f636b0d0a  
                                                                                                                            0190  782d636f6e74656e  742d747970652d6f  
                                                                                                                            01A0  7074696f6e733a20  6e6f736e6966660d  
                                                                                                                            01B0  0a0d0a557365722d  6167656e743a202a  
                                                                                                                            01C0  0a446973616c6c6f  773a200a0a536974  
                                                                                                                            01D0  656d61703a202f2f  6e6768747470322e  
                                                                                                                            01E0  6f72672f73697465  6d61702e786d6c20  
                                                                                                                            01F0  0a                                  

                                                                                                                            0000  .P°>cf.ê.ú.R...~
                                                                                                                            0010  P^..............
                                                                                                                            0020  HTTP/1.0 200 OK.
                                                                                                                            0030  .Date: Sat, 26 O
                                                                                                                            0040  ct 2019 21:07:32
                                                                                                                            0050   GMT..Content-Ty
                                                                                                                            0060  pe: text/plain..
                                                                                                                            0070  Last-Modified: M
                                                                                                                            0080  on, 19 Aug 2019
                                                                                                                            0090  13:20:36 GMT..Et
                                                                                                                            00A0  ag: "5d5aa224-3e
                                                                                                                            00B0  "..Accept-Ranges
                                                                                                                            00C0  : bytes..Content
                                                                                                                            00D0  -Length: 62..X-B
                                                                                                                            00E0  ackend-Header-Rt
                                                                                                                            00F0  t: 0.001315..Con
                                                                                                                            0100  nection: close..
                                                                                                                            0110  Server: nghttpx.
                                                                                                                            0120  .Via: 2 nghttpx.
                                                                                                                            0130  .alt-svc: h3-23=
                                                                                                                            0140  ":4433"; ma=3600
                                                                                                                            0150  ..x-frame-option
                                                                                                                            0160  s: SAMEORIGIN..x
                                                                                                                            0170  -xss-protection:
                                                                                                                            0180   1; mode=block..
                                                                                                                            0190  x-content-type-o
                                                                                                                            01A0  ptions: nosniff.
                                                                                                                            01B0  ...User-agent: *
                                                                                                                            01C0  .Disallow: ..Sit
                                                                                                                            01D0  emap: //nghttp2.
                                                                                                                            01E0  org/sitemap.xml
                                                                                                                            01F0  .               
                                                                                                                            • Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 1, Ack: 86, Len: 465
                                                                                                                              • Source Port: 80
                                                                                                                                • Destination Port: 45118
                                                                                                                                  • TCP Segment Len: 465
                                                                                                                                    • Sequence number: 1 (relative sequence number)
                                                                                                                                      • Acknowledgment number: 86 (relative ack number)
                                                                                                                                        • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                                          • Window size value: 126
                                                                                                                                            • Calculated window size: 64512
                                                                                                                                              • Window size scaling factor: 512
                                                                                                                                                • Checksum: 0x505e [unverified]
                                                                                                                                                  • Urgent pointer: 0
                                                                                                                                                    • TCP payload (465 bytes)
                                                                                                                                                    • Hypertext Transfer Protocol
                                                                                                                                                      • HTTP/1.0 200 OK\r\n
                                                                                                                                                        • Response Version: HTTP/1.0
                                                                                                                                                          • Status Code: 200
                                                                                                                                                            • Status Code Description: OK
                                                                                                                                                              • Response Phrase: OK
                                                                                                                                                              • Date: Sat, 26 Oct 2019 21:07:32 GMT\r\n
                                                                                                                                                                • Content-Type: text/plain\r\n
                                                                                                                                                                  • Last-Modified: Mon, 19 Aug 2019 13:20:36 GMT\r\n
                                                                                                                                                                    • Etag: "5d5aa224-3e"\r\n
                                                                                                                                                                      • Accept-Ranges: bytes\r\n
                                                                                                                                                                        • Content-Length: 62\r\n
                                                                                                                                                                          • Content length: 62
                                                                                                                                                                          • X-Backend-Header-Rtt: 0.001315\r\n
                                                                                                                                                                            • Connection: close\r\n
                                                                                                                                                                              • Server: nghttpx\r\n
                                                                                                                                                                                • Via: 2 nghttpx\r\n
                                                                                                                                                                                  • alt-svc: h3-23=":4433"; ma=3600\r\n
                                                                                                                                                                                    • x-frame-options: SAMEORIGIN\r\n
                                                                                                                                                                                      • x-xss-protection: 1; mode=block\r\n
                                                                                                                                                                                        • x-content-type-options: nosniff\r\n
                                                                                                                                                                                          • \r\n
                                                                                                                                                                                            • File Data: 62 bytes
                                                                                                                                                                                            0000  b03e005095fa0352  63660fbb800000ea  
                                                                                                                                                                                            0010  d0a80000                            

                                                                                                                                                                                            0000  °>.P.ú.Rcf.»...ê
                                                                                                                                                                                            0010  Ð¨..            
                                                                                                                                                                                            • Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 86, Ack: 466, Len: 0
                                                                                                                                                                                              • Source Port: 45118
                                                                                                                                                                                                • Destination Port: 80
                                                                                                                                                                                                  • TCP Segment Len: 0
                                                                                                                                                                                                    • Sequence number: 86 (relative sequence number)
                                                                                                                                                                                                      • Acknowledgment number: 466 (relative ack number)
                                                                                                                                                                                                        • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                                                                                                          • Window size value: 234
                                                                                                                                                                                                            • Calculated window size: 234
                                                                                                                                                                                                              • Window size scaling factor: -1 (unknown)
                                                                                                                                                                                                                • Checksum: 0xd0a8 [unverified]
                                                                                                                                                                                                                  • Urgent pointer: 0
                                                                                                                                                                                                                  0000  0050b03e63660fbb  95fa03528000007e  
                                                                                                                                                                                                                  0010  d2020000                            

                                                                                                                                                                                                                  0000  .P°>cf.».ú.R...~
                                                                                                                                                                                                                  0010  Ò...            
                                                                                                                                                                                                                  • Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 466, Ack: 86, Len: 0
                                                                                                                                                                                                                    • Source Port: 80
                                                                                                                                                                                                                      • Destination Port: 45118
                                                                                                                                                                                                                        • TCP Segment Len: 0
                                                                                                                                                                                                                          • Sequence number: 466 (relative sequence number)
                                                                                                                                                                                                                            • Acknowledgment number: 86 (relative ack number)
                                                                                                                                                                                                                              • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                                                                                                                                • Window size value: 126
                                                                                                                                                                                                                                  • Calculated window size: 64512
                                                                                                                                                                                                                                    • Window size scaling factor: 512
                                                                                                                                                                                                                                      • Checksum: 0xd202 [unverified]
                                                                                                                                                                                                                                        • Urgent pointer: 0
                                                                                                                                                                                                                                        0000  b03e005095fa0352  63660fbc800000ea  
                                                                                                                                                                                                                                        0010  d0a60000                            

                                                                                                                                                                                                                                        0000  °>.P.ú.Rcf.¼...ê
                                                                                                                                                                                                                                        0010  Ð¦..            
                                                                                                                                                                                                                                        • Transmission Control Protocol, Src Port: 45118, Dst Port: 80, Seq: 86, Ack: 467, Len: 0
                                                                                                                                                                                                                                          • Source Port: 45118
                                                                                                                                                                                                                                            • Destination Port: 80
                                                                                                                                                                                                                                              • TCP Segment Len: 0
                                                                                                                                                                                                                                                • Sequence number: 86 (relative sequence number)
                                                                                                                                                                                                                                                  • Acknowledgment number: 467 (relative ack number)
                                                                                                                                                                                                                                                    • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                                                                                                                                                      • Window size value: 234
                                                                                                                                                                                                                                                        • Calculated window size: 234
                                                                                                                                                                                                                                                          • Window size scaling factor: -1 (unknown)
                                                                                                                                                                                                                                                            • Checksum: 0xd0a6 [unverified]
                                                                                                                                                                                                                                                              • Urgent pointer: 0
                                                                                                                                                                                                                                                              0000  0050af725515391c  14178134a000fe88  
                                                                                                                                                                                                                                                              0010  f4f50000                            

                                                                                                                                                                                                                                                              0000  .P¯rU.9....4..þ.
                                                                                                                                                                                                                                                              0010  ôõ..            
                                                                                                                                                                                                                                                              • Transmission Control Protocol, Src Port: 80, Dst Port: 44914, Seq: 0, Ack: 1, Len: 0
                                                                                                                                                                                                                                                                • Source Port: 80
                                                                                                                                                                                                                                                                  • Destination Port: 44914
                                                                                                                                                                                                                                                                    • TCP Segment Len: 0
                                                                                                                                                                                                                                                                      • Sequence number: 0 (relative sequence number)
                                                                                                                                                                                                                                                                        • Acknowledgment number: 1 (relative ack number)
                                                                                                                                                                                                                                                                          • 1010 .... = Header Length: 40 bytes (10)
                                                                                                                                                                                                                                                                            • Window size value: 65160
                                                                                                                                                                                                                                                                              • Calculated window size: 65160
                                                                                                                                                                                                                                                                                • Checksum: 0xf4f5 [unverified]
                                                                                                                                                                                                                                                                                  • Urgent pointer: 0
                                                                                                                                                                                                                                                                                  0000  af72005014178134  0000000050000000  
                                                                                                                                                                                                                                                                                  0010  b85b0000                            

                                                                                                                                                                                                                                                                                  0000  ¯r.P...4....P...
                                                                                                                                                                                                                                                                                  0010  ¸[..            
                                                                                                                                                                                                                                                                                  • Transmission Control Protocol, Src Port: 44914, Dst Port: 80, Seq: 1, Len: 0
                                                                                                                                                                                                                                                                                    • Source Port: 44914
                                                                                                                                                                                                                                                                                      • Destination Port: 80
                                                                                                                                                                                                                                                                                        • TCP Segment Len: 0
                                                                                                                                                                                                                                                                                          • Sequence number: 1 (relative sequence number)
                                                                                                                                                                                                                                                                                            • Acknowledgment number: 0
                                                                                                                                                                                                                                                                                              • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                                                                                                                                                                • Window size value: 0
                                                                                                                                                                                                                                                                                                  • Calculated window size: 0
                                                                                                                                                                                                                                                                                                    • Window size scaling factor: 128
                                                                                                                                                                                                                                                                                                      • Checksum: 0xb85b [unverified]
                                                                                                                                                                                                                                                                                                        • Urgent pointer: 0
                                                                                                                                                                                                                                                                                                        0000  0050b03e63660fbc  95fa03538000007e  
                                                                                                                                                                                                                                                                                                        0010  d0230000                            

                                                                                                                                                                                                                                                                                                        0000  .P°>cf.¼.ú.S...~
                                                                                                                                                                                                                                                                                                        0010  Ð#..            
                                                                                                                                                                                                                                                                                                        • Transmission Control Protocol, Src Port: 80, Dst Port: 45118, Seq: 467, Ack: 87, Len: 0
                                                                                                                                                                                                                                                                                                          • Source Port: 80
                                                                                                                                                                                                                                                                                                            • Destination Port: 45118
                                                                                                                                                                                                                                                                                                              • TCP Segment Len: 0
                                                                                                                                                                                                                                                                                                                • Sequence number: 467 (relative sequence number)
                                                                                                                                                                                                                                                                                                                  • Acknowledgment number: 87 (relative ack number)
                                                                                                                                                                                                                                                                                                                    • 1000 .... = Header Length: 32 bytes (8)
                                                                                                                                                                                                                                                                                                                      • Window size value: 126
                                                                                                                                                                                                                                                                                                                        • Calculated window size: 64512
                                                                                                                                                                                                                                                                                                                          • Window size scaling factor: 512
                                                                                                                                                                                                                                                                                                                            • Checksum: 0xd023 [unverified]
                                                                                                                                                                                                                                                                                                                              • Urgent pointer: 0