I am running mpirun (Open MPI) 1.8.5 on my Mac OSX 10.9, but when I try
mpirun -np 4 run.exe
the terminal just hangs and eventually I get an error message
A process or daemon was unable to complete a TCP connection
to another process:
Local host: my_computer_name
Remote host: 10.0.0.15
This is usually caused by a firewall on the remote host. Please
check that any firewall (e.g., iptables) has been disabled and
try again.
Now, if I turn off my Wifi, everything works fine. Also, I do not have any firewall enabled. It's really annoying to have to turn off my wifi everytime I need to run mpi. Any ideas?
See this question and its answers. You need to tell MPI explicitely not to use the wifi, then it will survive disabling the wifi.
What happens is, that MPI greedily uses all IP networks it can muster,
thus, when you disable wifi, MPI looses one of the IP connections it uses.
Related
Thanks in advance for the help.
Issue:
Unable to receive snmp-traps on udp 162 port.
Scenario: Trying to put a nexus 5672 in OpenNMS for monitoring
Pre-Checks done:
I am able to snmpwalk the nexus 5k from my linux node on which
OpenNMS is installed.
I am even able to do snmpgets.
I see snmp traffic on udp 161 but they are primarily because of the snmp-get's that opennms is doing.
UNABLE TO SEE ANYTHING WHEN I DO A TCPDUMP ON 162 PORT :(
I have checked if any ACLs are set locally but they are not, iptables as a service is stopped.
I have verified that the snmp-configs are properly pushed.
Configs are pushed on the loop-back interface and there are not acl-groups on the nexus 5k either and there is not firewall between the nexus 5k and the OpenNMS Hosted Linux System
Please help, i do not know what i am missing.
Ok, first of all, there are two concepts with SNMP, the first one is polling for data to get data from sensors or discover elements from your device. The monitoring application sends requests to your Nexus device. This is what you do when you issue a snmpwalk or snmpget command. The Nexus device has an SNMP agent running which is listening on port 161/UDP.
The second one is, your Nexus device can send messages to your monitoring application. Your monitoring application with OpenNMS needs to have a listener running on port 162/UDP, called SNMP Traps or SNMP Informs.
So trying to debug the problem not getting SNMP Traps with snmpget or snmpwalk does not help in the first place. The communication is initialized by the Nexus device and OpenNMS is the listener for the traps.
I would try to debug the problem with the following steps:
Ensure OpenNMS has Trapd enabled and is listening on the right interfaces, e.g. with ss -lnpu sport = :162
Make sure you don't have a firewall on your OpenNMS server which blocks traffic to 162/UDP, e.g. iptables -L
Use tcpdump to see if the SNMP trap from your Nexus arrives on the OpenNMS server by looking at traffic with target port 162 with protocol UDP.
If you're SNMP trap is received from the OpenNMS server, you can then start looking in trapd.log of your OpenNMS server and verify if community settings for the IP is correct. OpenNMS will use the community which is configured for the senders IP address to process the trap
In hope this helps
This got resolved. Everything from the Linux end, and the OpenNMS SNMP end was good. However, the network device had SNMP configs wrongly pushed. I changed it to use the default VRF rather than the loopback address, and it started working.
I am having some trouble with my asterisk install hanging up calls.
Initially I was having no audio on my calls so I opened up the ports to my gsu gateway which is on a different network then my asterisk box. I opened up the port on the gsm gateway side with is behind not and that resolved the audio issues
Now the issue is that asterisk drops the calls. I have checked and the rtp packets stream is only sending packets and doesn't seem to be getting anything back.
The asterisk box is hosted on vultr with Ubuntu server.
Any idea on whats going on?
Hangup in 10-12 seconds after call started usually issued by incorrect nat settings. Asterisk can't send back response to softphone/hardphone and hangup line(it think no internet connection to device).
See http://www.voip-info.org/wiki/view/Asterisk+SIP+NAT+solutions
In your case it also can be firewall or bad virtualization setup.
I have some device in MIPS architecture, on this device unfortunately wasn't instal any server ssh, but telnet daemon is present. I try connect to this device in goal remote debbuging but I do not can connect. Also If I try test connect.
So it is possible to remote debugging in Qt trought Telnet ? Whether this function is only reserved for SSH server ?
I have a puzzle I am not able to figure out, I would appreciate any help.
I am connected to a remote desktop using windows default remote desktop utility (Windows 8 locally, Windows 7 remotely).
The remote desktop is not in the same sub-network as my own.
Connection is made through default port 3389. Using Wireshark locally I can confirm the TCP connection being established and the data flow.
Running Wireshark in the remote desktop, I don`t see any flow of data between the two computers.
If I send a ICMP ping from the remote desktop to my computer, it works well and I can see it in Wireshark both remotely as well as locally. But if I send the ICMP ping from my computer to the remote desktop, it fails. I see it leaving my computer through Wireshark, but it never reaches the remote desktop (I don`t see it in Wireshark).
I don't think it is a firewall issue (specially since it can't explain why Wireshark won`t capture the port 3389 RPC flow).
Does anyone have any idea of what might be going on?
I found the main issue.
In Wireshark, turns out it is possible to configure the capture interface with a filter.
To change it, go to: Capture->Interfaces
On the interface being used, stop capturing to enable the Options, there it is possible to configure a capture filter.
This issues started recently when I am trying to start active-mq (which by default starts on port 61616). But suddenly it stopped coming up with JVM_BIND issue on that port. The problem did not go away even after restarting the computer.
Main problem is that
netstat -a command on Windows 7, does not show that 61616 is consumed. But when I wrote a simple Java program to bind a socket to that port, I wasn't certainly able to!
I eventually started active-mq by moving to a different port. But, can anybody please help me find why all the ports are not showing up in netstat -a result? Thanks.
Don't use ephemeral ports:
http://www.ncftp.com/ncftpd/doc/misc/ephemeral_ports.html
What is the largest TCP/IP network port number allowable for IPv4?