[ale] lightweight testing for remote services

[Cory T. Echols]

On 03/21, Keith Hopkins wrote:
> Anyone know a lightweight way to test if a service
> (dns,http,ssh,insert-your-favorite-protocol-here) is being serviced on
> a remote server?

<Example using nmap snipped>

You could use netcat (nc) with the -z flag.  I'm not an experienced
benchmarker by any means, by my own rudimentary testing shows it to be a
decent amount lighter than an nmap invocation.

Here's an example checking for an open ssh port on my machine.

{1:~}$ time nmap -p 22 localhost

Starting nmap V. 3.10ALPHA4 ( www.insecure.org/nmap/ )
Interesting ports on localhost (127.0.0.1):
Port	   State       Service
22/tcp	   open        ssh

Nmap run completed -- 1 IP address (1 host up) scanned in 0.380 seconds
nmap -p 22 localhost  0.12s user 0.08s system 46% cpu 0.431 total

{2:~}$ time nc -v -z localhost 22
localhost [127.0.0.1] 22 (ssh) open
nc -v -z localhost 22  0.00s user 0.00s system 0% cpu 0.003 total

-- 
Cory T. Echols          | "The contest, for ages, has been to rescue liberty
ctechols at mindspring.com | from the grasp of executive power."
                        | 	--Daniel Webster
                        |
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