When I attempt to ping or SSH into the Ras-Pi it returns with nothing. The pi generally comes back after around an hour and I have no idea why? Hosting on "Apache2"
It probably because your power adapter cannot provide enough power, for Raspi 4B, it requires 5V--2A, hope that'll solve your problem.
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To make it simple, lets assume my company makes cables. I need an easy tool to validate that our cables fully support 100Mb Ethernet connection without any package lost. Is there a program / tool which can perform a full speed test of like an hour and monitor the lost packages as well?
Thanks!
You might have some luck with iPerf. It can stress-test a network connection and measure packet loss. You'd put an iPerf server at one end of the cable, and run the client on a machine at the other end.
To validate a twisted-pair cable for Cat-5e, Cat-6 or Cat-6A you need a professional cable tester (starts at 1000€ or so). Everything else is just try and error. You cannot seriously certify a cable using commodity hardware and some software.
What does it mean when the terminal throw this error and how to solve it?
packet_write_wait: Connection to xxx.xxx.xxx.xxx: Broken pipe
It was just happen today. After it work normally for year.
My terminal keep disconnect at a certain time. I had already search on google but most of it is about "Write failed: Broken pipe."
Which I already solved that for years. I just found this new annoyed problems today
I experienced this problem as well and spent a few days trying to bisect it.
Like specified, playing with SSH KeepAlive parameters (ClientAliveInterval, ClientAliveCountMax, ServerAliveInterval and ServerAliveCountMax) or kernel TCP parameters (TCPKeepAlive on/off) does not solve the problem.
After playing with USB to Ethernet drivers and tcpdump, I realized the issue was due to the kernel 4.8 I was using. I switched the source (sending side) to 4.4 LTS and the problem disappeared (rsync via ssh and scp were working nicely again). The destination side can remain on 4.8 if you want, in my use case this was working (tested).
On the technical side, we can narrow a little bit the issue thanks to the wireshark dump below I made. We can see the TCP channel of the SSHv2 protocol is being reset (RST flag of TCP set to 1) causing the connection to abort. I don't know the cause of that RST yet. I need to make some bisection from 4.8.1 to 4.8.11 for that.
I'm not saying your problem is specifically due to the kernel 4.8, but wrt. the date you posted your question/message, there are high chances you are currently using a kernel more recent than 4.4.
If that is an ssh connection, then you might want to make sure you send a keepalive message to the server.
ServerAliveInterval seems to be the most common strategy to keep a connection alive. To prevent the broken pipe problem, here is the ssh config I useed in my .ssh/ssh_config file (may be named as /etc/ssh/config or sshd_config):
Host myhostshortcut
HostName myhost.com
User barthelemy
ServerAliveInterval 60
ServerAliveCountMax 10
Connect through another wifi.
I don't know why or how it works, but it does.
The original poster sthapaun already mentioned this solution in a comment, but I want to add that the solution works for me, too.
Sorry for asking such a mundane question, but I'm suddenly curious. If I open the network connections dialog on my Windows machine, it shows me a cute little picture of my computer connecting to a router and then to a globe (labeled Internet). What is Windows trying to connect to in order for it to decide that the computer has Internet connectivity? I assume there is no IP4 address for 'The Internet', so where is it going? Is it just sending a ping to an address back at the Microsoft home office? If that address were to disappear, would my window's machine suddenly decide that it no longer has a route to the Internet? Would Windows boxes that were 'close' to that address incorrectly report that they could get to the Internet when they couldn't.
I'll stop now before this gets too silly. But seriously, what criteria does a Windows box use to determine that it has Internet connectivity? I'm assuming that Linux and iOS systems have an equivalent feature. Do they use the same criteria?
The general IP address that is used for 'the internet' is 8.8.8.8 - or Google.com.
If you can ping it, and get a web page from it, then there's a pretty good chance you can get to at least some of the internet.
But for specifically Windows - Network Connectivity Status Indicator - it uses a different domain: dns.msftncsi.com
It will (unless disabled by GPO):
resolve the name, and verify it has the 'right' IP (131.107.255.255
fd3e:4f5a:5b81::1 )
Perform a HTTP get to this address and check it gets a result. NCSI
Presumably if different responses are retrieved, then it can tell if it has a wi-fi login or similar.
Your intuitions seem correct. I am not on a Windows machine but you could find out by firing netstat and then connecting.
If I was programming this I'd make Ping, TCP and HTTP requests. Some devices are connected through proxies such as firewalls, captive portals and others. the only way to be sure is to send something and receive a reply.
My Android device for example can detect captive portals. It probably does that by trying to HTTP connect somewhere.
I have had this irritating issue for some time now. Basically, I like to leave my iMac sleeping but leave it listening for WOL packets for remote access. I know that Macs will wake every 2 hours or so to register with their base station (if you have one) but they immediately return to sleep.
My problem is that due to whatever reason (presumably something like bots sending out magic packets to random IP addresses and trying passwords to gain access) whenever the Mac receives a magic packet, it wakes (display still off) but doesn't go back to sleep if it receives no further network activity.
I downloaded sleepwatcher but I'm not really sure how to use it properly. I think I basically need a very small piece of code that waits maybe 30 seconds and if no network connectivity is detected, goes back to sleep. I know that requesting code is usually frowned upon here and I usually don't but in this instance, I'm struggling with where to even begin.
As a side question, is it possible to log the IP address that sent the magic packet? That could be helpful too, if it is coming from the same IP, I can simply block it.
I'd really appreciate any help on this.
Thanks,
Scott
stupid problem. I get those from a client connecting to a server. Sadly, the setup is complicated making debugging complex - and we run out of options.
The environment:
*Client/Server system, both running on the same machine. The client is actually a service doing some database manipulation at specific times.
* The cnonection comes from C# going through OleDb to an EasySoft JDBC driver to a custom written JDBC server that then hosts logic in C++. Yeah, compelx - but the third party supplier decided to expose the extension mechanisms for their server through a JDBC interface. Not a lot can be done here ;)
The Symptom:
At (ir)regular intervals we get a "Address already in use: connect" told from the JDBC driver. They seem to come from one particular service we run.
Now, I did read all the stuff about port exhaustion. This is why we have a little tool running now that counts ports and their states every minute. Last time this happened, we had an astonishing 370 ports in use, with the count rising to about 900 AFTER the error. We aleady patched the registry (it is a windows machine) to allow more than the 5000 client ports standard, but even then, we are far far from that limit to start with.
Which is why I am asking here. Ayneone an ide what ELSE could cause this?
It is a Windows 2003 Server machine, 64 bit. The only other thing I can see that may cause it (but this functionality is supposedly disabled) is Symantec Endpoint Protection that is installed on the server - and being capable of actinc as a firewall, it could possibly intercept network traffic. I dont want to open a can of worms by pointing to Symantec prematurely (if pointing to Symantec can ever be seen as such). So, anyone an idea what else may be the cause?
Thanks
"Address already in use", aka WSAEADDRINUSE (10048), means that when the client socket prepared to connect to the server socket, it first tried to bind itself to a specific local IP/Port pair that was already in use by another socket, either an active one or one that has been closed but is still in the FD_WAIT state. This has nothing to do with the number of ports that are available.
I'm having the same issue on a Windows 2000 Server with a .Net application connecting to a SQL Server 7.0. There's like 10 servers with the same configuration and only one is showing this error several times a day. With a small test program I'm able to reproduce the error by just establishing a TCP connection on the SQL Server listening port. Running CurrPorts (http://www.nirsoft.net/utils/cports.html) shows there's still plenty of available ports in range 1024-5000.
I'm out of ideas and would like to know if you've found a solution since you've posted your question.
Edit : I finally found the solution : a worm was present on the server (WORM_DOWNAD.A) and exhausted local ports without being noticed.