[CentOS] testing a udp socket with netcat

Arif Hossain freefall1986 at gmail.com
Wed Mar 14 09:59:38 EDT 2012


On Wed, 2012-03-14 at 08:37 -0500, Les Mikesell wrote:
> On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain <freefall1986 at gmail.com> wrote:
> > i've this udp daemon which is waiting for an incoming udp datagram. now
> > 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 does
> > not returns from recv() call.
> >
> > my goal is to ppience regarding netcat so i'm asking if anyone can help 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


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