最近想写个脚本来实现网段扫描，判断有哪些ip在用，最简单的就是将子网内的ip ping个遍。网上找了下貌似python都是通过调用系统来实现ping，在需ping的ip数量多的时候效率太低，自己写又重复造轮子。在网上找到了个ping的代码:
https://github.com/samuel/python-ping/blob/master/ping.py
这代码通过socket发送icmp包，通过select来获取reply，但代码是在python2上运行的，需将print和xrange之类的全改成python3的。
但改完后还是报错，首先报错的是这里
header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, my_checksum, ID, 1)
bytesInDouble = struct.calcsize("d")
data = (192 - bytesInDouble) * "Q"
data = struct.pack("d", default_timer()) + data
my_checksum = checksum(header + data)
struct后的header是byte，但却将字符串和byte相加了，考虑到data是icmp的内容，直接改为b’Q‘即可。
接下来报错的是ord函数
def checksum(source_string):
"""
I'm not too confident that this is right but testing seems
to suggest that it gives the same answers as in_cksum in ping.c
"""
sum = 0
countTo = (len(source_string)/2)*2
count = 0
while count<countTo:
thisVal = ord(source_string[count + 1])*256 + ord(source_string[count])
sum = sum + thisVal
sum = sum & 0xffffffff # Necessary?
count = count + 2
if countTo<len(source_string):
sum = sum + ord(source_string[len(source_string) - 1])
sum = sum & 0xffffffff # Necessary?
sum = (sum >> 16) + (sum & 0xffff)
sum = sum + (sum >> 16)
answer = ~sum
answer = answer & 0xffff
# Swap bytes. Bugger me if I know why.
answer = answer >> 8 | (answer << 8 & 0xff00)
return answer
source_string是byte，校验和也算的不对
将校验和字段置为0。
将每两个字节（16位）相加（二进制求和）直到最后得出结果，若出现最后还剩一个字节继续与前面结果相加。
(溢出)将高16位与低16位相加，直到高16位为0为止。
将最后的结果（二进制）取反。
修改校验和过程后，能正常ping了。
import os, sys, socket, struct, select, time
if sys.platform == "win32":
# On Windows, the best timer is time.clock()
default_timer = time.clock
else:
# On most other platforms the best timer is time.time()
default_timer = time.time
# From /usr/include/linux/icmp.h; your milage may vary.
ICMP_ECHO_REQUEST = 8 # Seems to be the same on Solaris.
def checksum(source_string):
"""
I'm not too confident that this is right but testing seems
to suggest that it gives the same answers as in_cksum in ping.c
"""
sum = 0
countTo = (len(source_string) / 2) * 2
count = 0
while count < countTo:
thisVal = (source_string[count + 1] << 8) + source_string[count]
sum = sum + thisVal
# sum = sum & 0xffffffff # Necessary?
count = count + 2
if countTo < len(source_string):
sum = sum + source_string[len(source_string) - 1]
# sum = sum & 0xffffffff # Necessary?
sum = (sum >> 16) + (sum & 0xffff)
sum = sum + (sum >> 16)
answer = ~sum
answer = answer & 0xffff
# Swap bytes. Bugger me if I know why.
answer = answer >> 8 | (answer << 8 & 0xff00)
return answer
def receive_one_ping(my_socket, ID, timeout):
"""
receive the ping from the socket.
"""
timeLeft = timeout
while True:
startedSelect = default_timer()
whatReady = select.select([my_socket], [], [], timeLeft)
howLongInSelect = (default_timer() - startedSelect)
if whatReady[0] == []: # Timeout
return
timeReceived = default_timer()
recPacket, addr = my_socket.recvfrom(1024)
icmpHeader = recPacket[20:28]
type, code, checksum, packetID, sequence = struct.unpack(
"bbHHh", icmpHeader
)
# Filters out the echo request itself.
# This can be tested by pinging 127.0.0.1
# You'll see your own request
if type != 8 and packetID == ID:
bytesInDouble = struct.calcsize("d")
timeSent = struct.unpack("d", recPacket[28:28 + bytesInDouble])[0]
return timeReceived - timeSent
timeLeft = timeLeft - howLongInSelect
if timeLeft <= 0:
return
def send_one_ping(my_socket, dest_addr, ID):
"""
Send one ping to the given >dest_addr<.
"""
# Header is type (8), code (8), checksum (16), id (16), sequence (16)
my_checksum = 0
# Make a dummy heder with a 0 checksum.
header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, my_checksum, ID, 1)
bytesInDouble = struct.calcsize("d")
data = (192 - bytesInDouble) * b"Q"
data = struct.pack("d", default_timer()) + data
# Calculate the checksum on the data and the dummy header.
my_checksum = checksum(header + data)
# Now that we have the right checksum, we put that in. It's just easier
# to make up a new header than to stuff it into the dummy.
header = struct.pack(
"bbHHh", ICMP_ECHO_REQUEST, 0, socket.htons(my_checksum), ID, 1
)
packet = header + data
my_socket.sendto(packet, (dest_addr, 1)) # Don't know about the 1
def do_one(dest_addr, timeout):
"""
Returns either the delay (in seconds) or none on timeout.
"""
icmp = socket.getprotobyname("icmp")
try:
my_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
except socket.error as e:
raise # raise the original error
my_ID = os.getpid() & 0xFFFF
send_one_ping(my_socket, dest_addr, my_ID)
delay = receive_one_ping(my_socket, my_ID, timeout)
my_socket.close()
return delay
def ping(host, timeout=2, count=4):
"""
Send >count< ping to >dest_addr< with the given >timeout< and display
the result.
"""
dest_addr = socket.gethostbyname(host)
for i in range(count):
print("ping %s..." % dest_addr)
try:
delay = do_one(dest_addr, timeout)
except socket.gaierror as e:
print("failed. (socket error: '%s')" % e)
break
if delay == None:
print("failed. (timeout within %ssec.)" % timeout)
else:
delay = delay * 1000
print("get ping in %0.4fms" % delay)
if __name__ == '__main__':
ping("www.baidu.com")
下次尝试将它改为异步ping
