Hi Peter,
Peter Garrett schrieb:
On Fri, 04 Apr 2008 20:24:16 +0200
"ml@bortal.de" <ml@bortal.de> wrote:
i would like to send some data from a netcat client to a netcat server.
Can you set up the netcat server so that it echos what he recieves?
As I understand it, netcat acts as both a client and server, effectively,
depending on which end you look at it from

So I'm not sure what you mean
here.
Background: I would like to test my firewall setup if all my open ports
(tcp and udp) work. So i want to send some data and check if the same
data comes back.
Can netcat do that? (no i dont want to use nmap

)
You can use netcat ( nc ) to "scan" ports - for example:
I actually do not want to find open port, but test if my open ports can
be reached (UDP and TCP).
nc -w 2 -z name-or-IP 80
checks if the system at "name-or-IP" is listening on port 80 . The -w
option is a "timeout" in seconds. If successful, nc exits silently. If
not, you see an error message.
For example:
$ nc -w 2 -z archive.ubuntu.com 80 # OK - silent exit
$ nc -w 2 -z archive.ubuntu.com.bogus 80
archive.ubuntu.com.bogus: forward host lookup failed: Unknown host :
Connection timed out
A UDP Port never replies by default. Thats why i need some
client/server setup to check if the udp port is really open (or better:
if the udp port is allowed by the firewall inbetween!)
Thanks, Mario
Peter
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