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 put arbitrary data on the udp socket by netcat. i do not have any experience regarding netcat so i'm asking if anyone can help me out with this.
thanks in advance.
On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain freefall1986@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 put arbitrary data on the udp socket by netcat. i do not have any experience 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.
On Wed, 2012-03-14 at 08:37 -0500, Les Mikesell wrote:
On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain freefall1986@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
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 Hossainfreefall1986@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
And your INPUT chain rejects everything that is not matched by those lines above it.
You'll need a:
-A INPUT -p udp --dport <port> -j ACCEPT in there before you go to REJECT.
On Wed, 2012-03-14 at 14:11 +0000, Giles Coochey wrote:
--------------ms000000020507030501060609 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable
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 Hossainfreefall1986@gmail.com =
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.
Giles Coochey NetSecSpec Ltd UK Mobile: +44 7983 877 438 Business Email: giles.coochey@netsecspec.co.uk Email/MSN/Live Messenger: giles@coochey.net Skype: gilescoochey
--------------ms000000020507030501060609-- _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On 14/03/2012 14:56, Arif Hossain wrote:
On Wed, 2012-03-14 at 14:11 +0000, Giles Coochey wrote:
--------------ms000000020507030501060609 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable
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 Hossainfreefall1986@gmail.com =
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?
On Thu, Mar 15, 2012 at 3:56 AM, Arif Hossain freefall1986@gmail.com wrote:
On Wed, 2012-03-14 at 14:11 +0000, Giles Coochey wrote:
--------------ms000000020507030501060609 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable
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 Hossainfreefall1986@gmail.com =
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 the UDP daemon listening on 127.0.0.1 (localhost)?
Cheers,
Cliff
Arif,
You would want to run tcpdump (or some other sniffer() on the host server, so that you can confirm that there is two-way traffic. If tcpdump on the host server does not show any traffic from your client, something is blocking inbound. If you see traffic coming into the server, but nothing returning, you probably have issues around OSI layers 5-7. If you see a response, but you did not see from your client, then it may something blocking return traffic.
- Rilindo
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Arif Hossain Sent: Wednesday, March 14, 2012 8:25 AM To: centos@centos.org Subject: [CentOS] testing a udp socket with netcat
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 put arbitrary data on the udp socket by netcat. i do not have any experience regarding netcat so i'm asking if anyone can help me out with this.
thanks in advance.
-- "You have a voice" ----The King's Speech
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-
Arif Hossain -
Cliff Pratt -
Foster, Rilindo (Contractor) -
Giles Coochey -
Les Mikesell