试图让网络扫描仪在树莓派2（Python）上运行

Question

So I have a network scanner, but its not working. It's showing that every ip on the network from 127.0.0.1 to 127.0.0.254 is down. I know for sure that's not the case. Does anyone know what the problem is?

import socket, ping
from struct import unpack, pack

my_ip = socket.gethostbyname(socket.gethostname())
print "My computer IP address:", my_ip
my_deets = socket.gethostbyname_ex(socket.gethostname())
print "My computer details:", my_deets


subnet_mask = "255.255.255.0"

def ip2long(ip):
    """7
    Convert an IP string to long
    """
    return unpack(">L", socket.inet_aton(ip))[0]

def long2ip(ip):
    """
    Convert a long to IP string
    """
    return socket.inet_ntoa(pack('!L', ip))

# Applying the subnet mask to IP
addr = ip2long(my_ip)
mask = ip2long("255.255.255.0")
prefix = addr & mask

print "Base address for network", long2ip(prefix)

# Get the number of possible computers on our network
all_computers = ip2long("255.255.255.255")
num_computers = all_computers ^ mask

# Go through each computer
for ip_suffix in range(num_computers):
    # Try to ping a computer on the network
    test_ip = long2ip(prefix + ip_suffix)
    try:
        print "[*] Checking to see if host is up..."
        timeout = ping.do_one(test_ip, 1)
        print timeout
        if timeout != None:
            print "[+] Host is there:", test_ip
        print "-"*100
    except socket.error, e:
        print "[-] Host not there:", test_ip

Answer 1

Your script does work (and it's kind of fun, though I'll prefer nmap ;) ).

However

• do_one takes a third argument, psize don't know how it works on your side.
• You need to be root (eg administrator). And your script mixes up the "failure" and "host down" cases. When a host is down, the function will return None . When an error occurs, it means that the ping could not be sent. So the fact that "It's showing that every ip on the network from 127.0.0.1 to 127.0.0.254 is down" , means actually that no packets could be sent.
• 127.0.0.1 is the loopback interface . There will be no other computer than yours on that network. The fact that socket.gethostbyname(socket.gethostname()) returns that address could mean that your network is improperly set. In some old days, the 127.0.0.1 address was hardlinked to the localhost hostname in the /etc/hosts file in order for some badly written programs (like Gnome apps at that time), who would wait for the IP associated with the hostname to respond or timeout before continuing with the start up, leading to extremely long delay to start the application each time the computer wasn't connected to any network. That workaround is no longer necessary IIRC.