Re: [CentOS] testing a udp socket with netcat
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-boun...@centos.org [mailto:centos-boun...@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 Public Key : $ gpg --keyserver keyserver.ubuntu.com --recv-key C88CFC23 This message, including any attachments, is the property of Sears Holdings Corporation and/or one of its subsidiaries. It is confidential and may contain proprietary or legally privileged information. If you are not the intended recipient, please delete it without reading the contents. Thank you. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
On Thu, Mar 15, 2012 at 3:56 AM, Arif Hossain freefall1...@gmail.com wrote: On Wed, 2012-03-14 at 14:11 +, Giles Coochey wrote: --ms00020507030501060609 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 Hossainfreefall1...@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 -uvvzhost 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 --dportport -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 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[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 Public Key : $ gpg --keyserver keyserver.ubuntu.com --recv-key C88CFC23 signature.asc Description: This is a digitally signed message part ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain freefall1...@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. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
On Wed, 2012-03-14 at 08:37 -0500, Les Mikesell wrote: On Wed, Mar 14, 2012 at 8:25 AM, Arif Hossain freefall1...@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 -- You have a voice The King's Speech Public Key : $ gpg --keyserver keyserver.ubuntu.com --recv-key C88CFC23 signature.asc Description: This is a digitally signed message part ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
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 Hossainfreefall1...@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 -uvvzhost 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 --dportport -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. -- Best Regards, Giles Coochey NetSecSpec Ltd UK Mobile: +44 7983 877 438 Business Email: giles.cooc...@netsecspec.co.uk Email/MSN/Live Messenger: gi...@coochey.net Skype: gilescoochey ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
On Wed, 2012-03-14 at 14:11 +, Giles Coochey wrote: --ms00020507030501060609 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 Hossainfreefall1...@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 -uvvzhost 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 --dportport -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.cooc...@netsecspec.co.uk Email/MSN/Live Messenger: gi...@coochey.net Skype: gilescoochey --ms00020507030501060609-- ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos signature.asc Description: This is a digitally signed message part ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] testing a udp socket with netcat
On 14/03/2012 14:56, Arif Hossain wrote: On Wed, 2012-03-14 at 14:11 +, Giles Coochey wrote: --ms00020507030501060609 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 Hossainfreefall1...@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 -uvvzhost 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 --dportport -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 --dportport -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.cooc...@netsecspec.co.uk Email/MSN/Live Messenger: gi...@coochey.net Skype: gilescoochey ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
