Re: testing a udp socket with netcat

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On 14/03/2012 14:56, Arif Hossain wrote:
On Wed, 2012-03-14 at 14:11 +0000, Giles Coochey wrote:
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On 14/03/2012 13:59, Arif Hossain wrote:
On Wed, 2012-03-14 at 08:37 -0500, Les Mikesell wrote:
On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain<freefall1986@xxxxxxxxx>  =
  wrote:
i've this udp daemon which is waiting for an incoming udp datagram. n=
ow
i want test this daemon for random garbage to test how it behaves. My=
udp daemon is running because its shows on netstat. problem is if i
issue following command for putting udp datagram :
$nc -uvvz<host>   <port>

it does not output any thing. i have straced the udp daemon. which do=
es
not returns from recv() call.

my goal is to ppience regarding netcat so i'm asking if anyone can he=
lp me
out with this.
Do you have iptables running?   The default config would probably
block your udp traffic.

here is my iptable-rules

# Generated by iptables-save v1.4.7 on Wed Mar 14 19:58:13 2012
*mangle
:PREROUTING ACCEPT [329554:95268521]
:INPUT ACCEPT [88918:46924677]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [7296:1924138]
:POSTROUTING ACCEPT [7296:1924138]
COMMIT
# Completed on Wed Mar 14 19:58:13 2012
# Generated by iptables-save v1.4.7 on Wed Mar 14 19:58:13 2012
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [206514:24743648]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport<port>   -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT
# Completed on Wed Mar 14 19:58:13 2012

And your INPUT chain rejects everything that is not matched by those=20
lines above it.

You'll need a:

-A INPUT -p udp --dport<port>  -j ACCEPT in there before you go to REJECT=
=2E

--=20
Best Regards,
for testing purpose i have flushed all rules in iptables -t filter

$iptables -t filter --flush

but still if try putting data by nc:

$nc -uvv localhost 7160

outputs :

write error: connection refused.


Is SELinux installed and Enforcing?

--
Best Regards,

Giles Coochey
NetSecSpec Ltd
UK Mobile: +44 7983 877 438
Business Email: giles.coochey@xxxxxxxxxxxxxxxx
Email/MSN/Live Messenger: giles@xxxxxxxxxxx
Skype: gilescoochey


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