Python-Scapy or the like-How can I create an HTTP GET request at the packet level

If you want to do a full three-way handshake, you'll have to do it manually.

Start with your SYN packet:

>>> syn = IP(dst='www.google.com') / TCP(dport=80, flags='S')>>> syn<IP  frag=0 proto=tcp dst=Net('www.google.com') |<TCP  dport=www flags=S |>>

Then receive the SYN-ACK packet from the server, sr1 works. Then send your HTTP GET request:

>>> syn_ack = sr1(syn)Begin emission:Finished to send 1 packets.*Received 1 packets, got 1 answers, remaining 0 packets>>> syn_ack<IP  version=4L ihl=5L tos=0x0 len=44 id=424 flags= frag=0L ttl=55 proto=tcp chksum=0x2caa src=74.125.226.148 dst=10.20.30.40 options=[] |<TCP  sport=www dport=ftp_data seq=3833491143 ack=1 dataofs=6L reserved=0L flags=SA window=5720 chksum=0xd8b6 urgptr=0 options=[('MSS', 1430)] |<Padding  load='\x00\x00' |>>>

Then set your TCP sequence and ack numbers and send the GET:

getStr = 'GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n'request = IP(dst='www.google.com') / TCP(dport=80, sport=syn_ack[TCP].dport,             seq=syn_ack[TCP].ack, ack=syn_ack[TCP].seq + 1, flags='A') / getStrreply = sr1(request)

FTR, as of Scapy 2.4.3, dissection of HTTP packets was implemented, among a util called "TCP_client" to do the 3 handshake automatically.

While it's not as teaching as the above answer, it doesn't hurt to have a look: https://scapy.readthedocs.io/en/latest/layers/http.html#use-scapy-to-send-receive-http-1-x

load_layer("http")req = HTTP()/HTTPRequest(    Accept_Encoding=b'gzip, deflate',    Cache_Control=b'no-cache',    Connection=b'keep-alive',    Host=b'www.secdev.org',    Pragma=b'no-cache')a = TCP_client.tcplink(HTTP, "www.secdev.org", 80)answser = a.sr1(req)a.close()

Have you had a look at the tutorial? Just copying and pasting, this looks like it's going to assemble an HTTP request:

>>>  a=Ether()/IP(dst="www.slashdot.org")/TCP()/"GET /index.html HTTP/1.0 \n\n"