From: john maclean <jayeola@...>
Date: 2008-08-30T13:01:36+09:00
Subject: Re: Ping.pingecho

2008/8/29 John Pritchard-williams <monojohnny@googlemail.com>:
> john maclean wrote:
>> Cisco.com don't normally allow pings so tracroutes and pings won't get
>> echo requests.
>>
>>
>> irb(main):003:0> Ping.pingecho('cisco.com', 10, 80)
>> => true
>>
>> How come this works and `ping` does not? From irb I see that Ruby's
>> ping uses a TCP echo. Also I've run tcpdump whilst running ping.echo
>> and could not determine the port that it uses. What port does Ruby's
>> Ping use?
>
> check out:
>
> http://www.noobkit.com/show/ruby/ruby/standard-library/ping/pingecho.html
>
> According to this the 'echo' port.
>
> grep'ing 'echo' in my /etc/services reveals this is port 7...apparently.
> (UDP and TCP).
>
>
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

Thanks for the reply. pinging on the echo port makes sense. However
one can ping a host for  service and get a response even if that
service is not actually running on the host.

services = %w{bacula-dir distcc echo fax git hostname http https icmpd
kermit keyserver ldap mbus msexch-routing mysql nmap postgres quake
rsync rwhois shell squid ssh svn telnet traceroute tunnel whoami wins
x11}

wooota = '192.168.1.1'

services.each do |x|
  p %Q{checking host #{host} for protocol #{x}}
  p Socket.getaddrinfo(host, x)
end


I get responses even though I __know__ that these services are __not__
running on my router. Is this because pingecho sends packets on port 7
regardless of the service that one requests?

-- 
John Maclean - 07739 171 531
MSc (DIC)