Reverse DNS lookup?

[ga rg]

I'm in an environment with a lot of computers that haven't been
properly inventoried. Basically, no one knows which IP goes with which
mac address and which hostname. So I wrote the following:

# This script goes down the entire IP range and attempts to
# retrieve the Hostname and mac address and outputs them
# into a file. Yay!

require "socket"

TwoOctets = "10.26"

def computer_exists?(computerip)
system("ping -c 1 -W 1 #{computerip}")
end

def append_to_file(line)
file = File.open("output.txt", "a")
file.puts(line)
file.close
end


def getInfo(current_ip)
begin
if computer_exists?(current_ip)
arp_output = `arp -v #{current_ip}`
mac_addr = arp_output.to_s.match(/..:..:..:..:..:../)
host_name = Socket.gethostbyname(current_ip)
append_to_file("#{host_name[0]} - #{current_ip} - #{mac_addr}\n")
end
rescue SocketError => mySocketError
append_to_file("unknown - #{current_ip} - #{mac_addr}")
end
end


(6..8).each do |i|
case i
when 6
for j in (1..190)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
when 7
for j in (1..255)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
when 8
for j in (1..52)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
end
end


Everything works except it does not find a Reverse DNS.

Sample output that I'm getting is this:

10.26.6.12 - 10.26.6.12 - 00:11:11:9B:13:9F
10.26.6.17 - 10.26.6.17 - 08:00:69:9A:97:C3
10.26.6.18 - 10.26.6.18 - 08:00:69:93:2C:E2

If I do `nslookup 10.26.6.12` then I get the correct reverse DNS so
that shows that my machine is seeing the dns server.

I have tried Socket.gethostbyname, gethostbyaddr, but it doesn't work :
(

Any guidance will be much appreciated. Thanks!

 

[Heesob Park]

Hi,

I'm in an environment with a lot of computers that haven't been
properly inventoried. Basically, no one knows which IP goes with which
mac address and which hostname. So I wrote the following:

# This script goes down the entire IP range and attempts to
# retrieve the Hostname and mac address and outputs them
# into a file. Yay!

require "socket"

TwoOctets = "10.26"

def computer_exists?(computerip)
system("ping -c 1 -W 1 #{computerip}")
end

def append_to_file(line)
file = File.open("output.txt", "a")
file.puts(line)
file.close
end


def getInfo(current_ip)
begin
if computer_exists?(current_ip)
arp_output = `arp -v #{current_ip}`
mac_addr = arp_output.to_s.match(/..:..:..:..:..:../)
host_name = Socket.gethostbyname(current_ip)
append_to_file("#{host_name[0]} - #{current_ip} - #{mac_addr}\n")
end
rescue SocketError => mySocketError
append_to_file("unknown - #{current_ip} - #{mac_addr}")
end
end


(6..8).each do |i|
case i
when 6
for j in (1..190)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
when 7
for j in (1..255)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
when 8
for j in (1..52)
current_ip = "#{TwoOctets}.#{i}.#{j}"
getInfo(current_ip)
end
end
end


Everything works except it does not find a Reverse DNS.

Sample output that I'm getting is this:

10.26.6.12 - 10.26.6.12 - 00:11:11:9B:13:9F
10.26.6.17 - 10.26.6.17 - 08:00:69:9A:97:C3
10.26.6.18 - 10.26.6.18 - 08:00:69:93:2C:E2

If I do `nslookup 10.26.6.12` then I get the correct reverse DNS so
that shows that my machine is seeing the dns server.

I have tried Socket.gethostbyname, gethostbyaddr, but it doesn't work :
(

Any guidance will be much appreciated. Thanks!

Try getaddrinfo like this:

s = Socket.getaddrinfo('10.26.6.12',nil)
hostname = s[0][2]


Regards,

Park Heesob

 

[ga rg]

Thank you very much. That works perfectly . Any reason why
getnamebyaddr didn't work because rubydocs seems to suggest that it
should.

Hi,

TwoOctets = "10.26"

append_to_file("unknown - #{current_ip} - #{mac_addr}")
end
end

If I do `nslookup 10.26.6.12` then I get the correct reverse DNS so
that shows that my machine is seeing the dns server.

I have tried Socket.gethostbyname, gethostbyaddr, but it doesn't work :
(

Any guidance will be much appreciated. Thanks!

Try getaddrinfo like this:

s = Socket.getaddrinfo('10.26.6.12',nil)
hostname = s[0][2]


Regards,

Park Heesob