I am trying to set up a distributed computing cluser via MPI (MPICH2), running on Windows XP. I am trying to run a single command, along the lines of
>> mpiexec -hosts 2 localhost 1 other-computer 2 notepad.exe
Aborting: unable to connect to other-computer
What are possible causes? I know that the network is fine, since ping works:
>> ping other-computer
Pinging other-computer [IPADDRESS] ...
Reply from IPADDRESS: bytes=32 time<1ms TTL=128
...
mpiexec.exe and smtpd.exe are both listed as exceptions in Windows Firewall.
What could be possible causes of this problem? My Google-fu has failed me! (Could it be something to do with authentication? I tried using -logon, but that doesn't change anything. If it might be an authentication problem, how can I find my own username / password (or does it use the computer username/password)?)
Please forgive ignorance, as I am unfamiliar with the workings of MPI.
Related
I run my MPJ program using 5 PCs with the same name (DESKTOP-J49PIF5) but it has different IP address. It run successfully in a laboratory. But when I tried to run the same program with the same configuration in a new laboratory (different place), I got "Connection refused" error.
More info that may help.
The same problem happened to my Apache Spark program, but I can solve the problem by adding "--conf “spark.driver.host=<<master_ip>>”" in the configuration. Someone said that the program can not find the driver host so we have to add that extra line in the configuration. Please note that in the previous laboratory I didn't add that line and either my MPJ and Spark program are working.
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Now, my problem is why I got "Connection refused" error in my MPJ program? If the problem is the same as Apache Spark then how can I configure the MPJ? Perhaps by adding master_ip similar to Apache Spark? But I don't know how to do it.
...
this error is repeated for 5 PCs.
After struggling for a few days, finally I found the answer. The problem was in the hostnames. Each PC has a different IP address and I can ping them. But, for cluster computing instead of using IP address, it uses the hostname to contact each other so we have to give a unique hostname for every PC. I changed all hostnames and the program is running fine.
Can using this command
nmap www.google.com
Cause dos attack. It gave me some output but I do not understand it. I have never used nmap before.
One computer trying to analyze one site is very unlikely to cause a denial of service to happen. You are more likely to run out of resources on your own machine before you put in any kind of dent in a properly set up web server.
Your question is kind of confusing. nmap primarily is a port scanner. It tries to to find open ports on a single or multiple selected targets (in your case www.google.com) by sending a TCP SYN package to every port (of the 1000 most used ports) and checking if an ACK package is received. If an ACK is received the port is considered open. Although port scanning can be regarded kind of malicious when done on a system not owned by you, it is not a dos attack when done once and from a single source system.
I would like to connect via ssh to certain equipment in a network.
The requisites are:
It must run a command and capture the output of the ssh session in R (or in bash, or any other programming language, but I would prefer it in R language)
It must enter a plain-text password (as this equipment hasn't been accessed before, and can't be changed with a rsa keypair), so the ssh.utils package doesn't meet this requirement
sshpass can't be used, as I have noticed that it doesn't work for some devices I tested.
I've read all this posts but I can't find an effective way to perform it: link 1, link 2, link 3, link 4
I know the requirements are hard to accomplish, but thank you for your effort!
EDIT:
Sorry if I didn't make myself understandable. I mean I work locally in R and I want to connect to +3000 devices in all of my network via ssh. It is Ubiquiti equipment, and the only open ports are 80 and 22.
If ssh doesn't work, I will use the RSelenium package for R and extract info from port 80. But first I will try with ssh pory 22 as it is a lot more efficient than opening an emulated browser.
The big problem in all these Ubiquiti equipment is that they have a password to log in. That's why requisite No.2 is needed. When I must enter a server that I know, I spend time setting up the rsa keypair so that I don't have to enter a password everytime I connect to a specific server, but it's impossible (or at least, for me it's impossible) to configure all +3000 Ubiquiti equipment with these keypairs.
That's why I don't use snmp, for example, as this equipment maybe they have it activated or not, or the snmp configuration is mistaken. I mean, I have to use something that's activated by default, and in a way, ordered. And only port 80 and port 22 are activated and I know all the user's and password's equipment.
And sshpass is an utility in UNIX/Linux like this link explains that works for servers but doesn't work for Ubiquiti equipment, as long as I've tested it. So I can't use it.
The command I need to extract the output from is mca-status. Simply by entering that into the console makes it print some stats I will like to get from the Ubiquiti equipment.
Correct me, please, if I am wrong in something I've posted. Thanks.
I think you have this wrong. I also have no idea what you are trying to say in point 2, and I have not idea what point 3 is supposed to say.
Now: ssh is a authentication mechanism allowing you (trusted) access to another machine and the ability to run a command. This can be as simple as
edd#max:~$ ssh bud Rscript -e '2+2'
[1] 4
edd#max:~$
where I invoke R (or rather, Rscript) on the machine 'bud' (my desktop) from a session on the machine 'max' (my server). That command could be anything including something which writes to temporary or permanent files. You can then retrieve those files via scp.
Authentication is handled independently -- on Unix we often use ssh-agent which run in the background and against you authenticate on login.
Finally I solved it using the rPython package and the python's paramiko module, as there was no way to do it purely via R.
library(rPython)
python.exec(python.code = c("import paramiko",
"ssh = paramiko.SSHClient()",
"ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())",
sprintf('ssh.connect("%s", username="USER", password="PASSWORD") ', IP),
'stdin, stdout, stderr = ssh.exec_command("mca-status")',
'stats = stdout.readlines()'))
I'm new to ubuntu and storm , i need to solve this problem
[ERROR] Async loop died!
org.zeromq.ZMQException: Address already in use(0x62)
at org.zeromq.ZMQ$Socket.bind(Native Method)
it appeared in worker log file due to supervisor still hasn't start and by searching found someone wrote that is due to
ephemeral port range was messed
up on the machines
tried to increase /proc/sys/net/ipv4/ip_local_port_range 1024 65000
but not working
This issue is related to already used ports in your system. A port can only be used by a single application. Using lsof -i you can check what application are using which ports. You should spot an conflicting port number. Either terminate this application of change the configuration of Zookeeper or Storm to use a different port.
How can I do inter-process communication between two remote process on unix C/C++? Currently, popen works for two process on same host? Product need to be capability to call remote process and send /receive the data.
As you mentioned popen you may not realize this already allows you to use ssh to remotely execute a process and treat exactly the same as a locally spawned one.
popen ("ssh user#remotehost /usr/bin/cal", "r")
And a pre-emptive link for further questions on ssh:
https://serverfault.com/questions/117007/ssh-key-questions
why would you nut just open the wild card % in the IP so that they could access the host.. remorely..
192.168.1.% something like that...:D