I'm using a Raspberry Pi, and upon startup it's sending an e-mail with the time and an IP address. The problem is that the time is not correct, it's the time from last time the system was shut down. When I log in through ssh and do a date command, I get the correct time. In other words, the e-mail is sent before the system has updated its time.
I was thinking of automatically running ntpdate on boot, but after reading up on it it seems like a bad idea due to the many risks of error.
So, can I somehow wait until the time has been uppdated before continuing in a script?
There is a tool included in the ntp reference implementation for this very purpose. The utility has a rather cryptic name: ntp-wait. Five minutes with the man page and you will be all set.
Related
Is there a way to skip a host while it is being scanned. I am providing a list of hosts to nmap and while it is scanning from that list, I would like to skip one host because the scripts keep running on that host hence delaying my scan. Please suggest.
Thanks
There is not a way during runtime to stop scanning a host. However, you can impose time limits on how long Nmap spends on a particular host. The --host-timeout option will cause Nmap to drop all results and stop scanning a target when the timeout expires. Unfortunately, this means all that work is lost. But there is a better way, if NSE scripts are slowing you down.
Nmap 7.30 added the --script-timeout option, which puts a time limit on each NSE script that runs against a target. Any script that exceeds the time limit will be terminated and will produce no output, but any other scripts will be allowed to run. No port scan, OS detection, or traceroute data will be lost.
Your last option if NSE is taking too long is to find out which script is causing the problem. Most NSE scripts are designed to run quickly; even most of the brute-force password guessing scripts enforce a 10-minute time limit. But sometimes there are bugs, and other times you may select a script with an intentionally long run time. In debug mode (-d or press d during runtime), printing a status line (by pressing any key during execution) will show a list of running scripts when there are 5 or fewer running. At debug level 2 (-dd or press d twice), a full stack trace of each running script thread is produced, which can help Nmap developers debug delays. If you suspect a misbehaving script, you can file a bug report on Github or send it to dev#nmap.org.
nmap has a host timeout option which will give up on any host that takes longer than the provided value. So, the below option would give up on any host that takes longer than 10 minutes. You can read more about the various timing related options here.
nmap --host-timeout 10m
I have a server that runs Postgresql. in the logs I am seeing this message for my resque based 'worker' box, multiple times a minute. Some minutes there isn't a message, others could be 10 times.
2016-01-12 13:40:36 EST:1.1.8.2(33899):[16141]: LOG: could not receive data from client: Connection reset by peer
Now when i go into the 1.1.8.2 box to look at netstat -ntp i don't see a port 33899, and most of them are at least in the 40xxx range by now. That may be conjecture but I'm at a loss to find out why a Redis/Resque/Puma Rails stack would be printing out these messages, let alone what that means even if i get to the bottom of it.
Will I gain memory back if they are closed 'normally'?
Is this a thing to be wary of?
How does one debug OLD ports that are open when the db box and the worker box both don't display the ports any more?
This message is probably due to the resque worker task not closing the database connection before it exits. It's not a huge problem, but presumably Postgres is doing a little extra work to clean it up, and it makes a mess of your log file...
One solution is to add a hook to your resque worker's task file (the same file that contains the self.perform definition):
def self.after_perform(*args)
ActiveRecord::Base.connection.disconnect!
end
I provide support for a large application across multiple servers. System has been running live for 6+ months.
8th December: total system failure. iisreset across each of the servers sorted it out. Everything back to normal.
Post failure investigation showed various processes not able to get a response from a particular server which hosts an instance of Dynamics CRM (2011 R11). Specifically it seems the SOAP service was not responding (Organization.svc). 503 - Server Unavailable (really it was just the web service). I suspect it died.
Having the exact time of the error I checked the event logs on the server but these did not have anything of use. The last error prior to the failure was a report rendering error which was 9 minutes before the system actually went down. Surely if web service crashed this would be reflected in the event log?
Fast forward to today, 8th January and the system fails again. The 8th of the month again! iisreset fixes it... again!
Again, completely useless event logs showings no errors prior to failure.
Entertained the idea of Dynamics CRM trace logging but this is out of the question due to the performance hit.
Apart from the event logs where else to look? Are there possible external factors or causes? I'm trying to find the root cause but have run out of ideas!
While this may not address the source of your problem, maybe it can help minimize the symptoms. May I suggest that you configure the IIS server to recycle the application pool at a scheduled interval within your production environment.
http://technet.microsoft.com/en-us/library/cc753179%28v=ws.10%29.aspx
I have a critical windows service that I need for my web application.
Unfortunately, the windows service does not start properly, but remains in a status of "Starting" for about 7 minutes and 38 seconds, and then fails.
My web application works fine when the service is in the "Starting" mode.
I have a windows scheduled task that runs every minute to restart the service if necessary.
net start "my service"
Therefore there is a gap of about 22 seconds from when the service fails until it starts up again. In additional it takes an additional 30 seconds or so for my application (which is dependent on this service) to start working.
I have intentionally not named the errant service. I did open a separate question https://stackoverflow.com/questions/8470975/oracle-oc4j-service-keeps-stopping whose aim was to actually solve the problem.
In this question, I am not trying to solve the problem, but rather find a workaround to try and keep this service in a status of "Starting" the whole time.
What is infuriating, is that until I restarted the server today, my workaround of restarting the service every 3 minutes actually worked, with no application downtime whatsoever.
Does anybody have any suggestions? I did try changing the registry key of ServicesPipeTimeout to 86400000 (24 hours!) in a bid to keep the service in the status of "Starting" for longer.
I have found a possible solution to my problem that I am very uneasy about...
I downloaded WinDbg from http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=8279
I opened WinDbg and did Attach to Process, and selected my service.
As long as WinDbg is open, it seems to "hold" the process and prevent it from stopping.
How long it will continue to do so, remains to be seen, but it has held for over half an hour now (whereas before the service stopped after 8 minutes)
If you have the timeout set to 24 hours and the service does not start or stay in 'starting' mode , then it must be either crashing or closing itself down.
If you want to try to restarting your service immediately it crashes, then, on the properties of your service, select the 'Recovery' tab. You should be able to set the service to restart on first, second and subsequent failures and set the service to restart after 0 minutes,
Note, this will not work if windows thinks that the service is closing down properly.
It should go without saying that this is a last resort only if you can't get whoever wrote the service to fix the problems.
Try specifying 'Restart the Service' for all three sections on the Recovery tab, but that will only work if the service is ending abnormally.
Our company faced a similar problem and we developed Service Protector, a commercial application that can babysit a service and keep it running 24/7. It may work in your situation too.
I run a Powershell script on a computer that has no Internet connection. But it takes about 30 seconds to start it. How do I solve it?
I have run ngen.
There is a known issue with certificate revocation list checks and .NET (which PowerShell is built on). Check out this post about the .NET issue.
Sounds like it might be trying to do a DNS lookup, and waits for it to time-out. I presume it doesn't take ~30 seconds to start on a machine with internet connection? You could try setting a bogus DNS resolver on the working machine, and see if it takes ~30 seconds there too.