I am using OpenSSH version13 in a project.
However every now and then nchan.c returns an error when we are trying to connect to the product using ssh, we get the following prints in the product and then the connection is closed.
channel 0: rcvd eof
output open -> drain
channel 0: obuf empty
channel 0: close_write
channel 0: output drain -> closed
All of these outputs are from nchan.c. Just reading the code and trying to see what might have happened seems impossible to me at least! Does anyone have any clue why OpenSSH might print this error messages and close the connection?
I am hoping that someone is very familiar with the OpenSSH implementation to point me to the right direction!
I am using python to connect to the product, more specifically the python pexpect module. I set up a SSH connection, log in with user name, password and then I perform some commands and check output. This works all fine most of the times, but as explained earlier the connections fails every now and then. The output provided above can be seen in the product, and from pexpect an exception is thrown that it received EOF (End Of File) from the product (meaning that a connection could not be set up). That is pretty much all the printouts I get. I hope that someone can understand why OpenSSH does not want to setup the connection!
When SSH debugging (-v) fails to give enough output, I always start sshd in debugging mode and watch from the sshd console directly. It tends to give more feedback on exactly what the root cause is.
If you are really using the version of OpenSSH you linked to, you are using an outdated version.
The latest version of OpenSSH nchan.c file can be found here: http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/nchan.c?rev=1.63;content-type=text%2Fx-cvsweb-markup and you can note the difference in version: 1.63 (dated 2010/01/26) vs 1.32 (dated 2001/10/10).
Please make sure you upgrade to the latest version of OpenSSH - I suspect you stumbled upon a bug that has been corrected a long time ago.
Related
I am trying to open an MS Access database in Base using the instructions here . (I've tried both .mdb and .accdb)
I can follow the process described by Gord with no problems until the last step, where it asks me to save the database in LibreOffice format. I choose a filename (say mylinuxdb.odb), click OK, and then Base opens with this error:
The connection to the data source "mylinuxdb" could not be established.
org/apache/commons/logging/LogFactory
Note that it is complaining about the new .odb database, not the MS Access database. Nonetheless, no data is imported.
Can anyone help with this?
Thank you.
Revised answer:
It appears that this issue is specific to distributions like Linux Mint that install LibreOffice Base by default. Presumably in order to enable embedded HSQLDB databases they also install a rather old version of HSQLDB which conflicts with UCanAccess. To fix that, remove LibreOffice's copy of HSQLDB. For Linux Mint that would be
sudo apt remove libhsqldb1.8.0-java
(original answer)
I was able to reproduce your issue with LibreOffice 6.4.6.2 on Xubuntu 20.04. It looks like the setup instructions on Ask Ubuntu may need to be tweaked.
In the meantime try opening your .odb file, clicking through any errors. When Base opens, choose
Edit > Database > Properties …
and notice that the "Database URL" text box has "jdbc:" in front of it.
so if the textbox contains
jdbc:ucanaccess:///home/gord/Documents/Database1.accdb
then apparently Base will try to use
jdbc:jdbc:ucanaccess:///home/gord/Documents/Database1.accdb
and that won't work. We need to have just
ucanaccess:///home/gord/Documents/Database1.accdb
in the text box (as in the screenshot above).
This is NOT (as per chosen answer) "specific to distributions like Linux Mint that install LibreOffice Base by default". Such statements should be avoided as they are clearly very difficult to prove except with rigorous analysis of all other situations, which is clear was not done and in practical terms cannot be done.
I just encountered this message with an LO Base form which uses a MariaDB installation on Windows 10, using a JDBC connection with the mysql-connector-java-8.0.28.jar connector .jar. The form was created only minutes previously.
Interestingly, I happened to have a Python application running at the same time but, and I stress, this Python application does not use any kind of connection to any mysql database whatsoever. Nor, being CPython, does it use Java in any way whatsoever.
I find that when I close the Python application I am then able to open the LO Base form. Furthermore, after having first opened the LO Base form I am then able to run the Python application.
As to why this ludicrous error should arise in these circumstances in the first place, I do not yet know. Chalk it down to yet one more LO anomaly and oddity around which you have to navigate by hook or by crook.
I can find nothing on how to do this. I am programming an Intel Edison in C and an Android phone in Java. I want to pair the Edison from the Android phone. I would think simple pairing (sspmode 1) would work but I get an error message on the phone about a wrong pin where no pin was requested. With sspmode 0 I get asked for a password but have no idea what it is as it is randomly generated in my NoInputNoOutput Edison. We have everything else working. If we pair from Edison manually, the rest of the code can connect and send bluetooth messages back and forth from the Edison to the phone. But pairing from Edison to any random phone that walks by is not acceptable. I think it is called Bluejacking.
I have seen some posts about using simple-agent but frankly what I understand is that BlueZ security changed so much between 4 and 5 that most all that I see doesn't work. I also see that the switch from 4 to 5 broke a lot of systems so I don't feel alone. I would try it but simple-agent is not on Edison and I have not found a procedure to install it. And as I don't know if the little I can find applies to version 5 as it all references version 4 I am feeling a little lost.
Can anyone point me in the right direction to something that will work on BlueZ 5? I am on 5.18.
The solution presented on the last post of this article does work
http://www.linuxquestions.org/questions/linux-wireless-networking-41/setting-up-bluez-with-a-passkey-pin-to-be-used-as-headset-for-iphone-816003/
Edit simple-agent, put it somewhere, make it executable, put the missing files in the same directory and run it. It must stay running for it to be active.
In my case, the missing file was bluezutils.py.
Run hciconfig hci0 sspmode 0 first
Pl use Bluz5.30.
Initially it was really difficult to bring up bluetooth using Bluez 5. It seems it was okay with Bluez 4.I have tried different versions of Bluez 5 on my LFS build. Even up to Bluez 5.28 it was not satisfactory. Now it is Bluz5.30, with this, LFS doc and lot of trail, I could manage. I feel Bluez is one of the most badly documented user unfriendly software. I also feel it is very buggy. It can hang machines forcing to hard boot the system. I have seen bluetooth forcing the Android phone also to reboot. So it is important to get the latest version of the software. But to make the bluetooth speaker work Pulseaudio was needed. It is better to get the latest version; here also LFS doc was fine.
So the process of connecting speaker was using bluetoothctl is as follows;
>> power on
>> scan on
>> pairable on
>> pair <device>
>> agent on
>> default-agent
Now the actual sound. Here pactl and pacmd are useful.
paplay -d can test the devices.
using pacmd with command 'list-sinks' can show the devices.
pacmd ->list-modules can show the modules loaded.
How to change automatically the audio output to bluetooth speaker when it is connected?
For me in one machine it was working fine, with an identical LFS in another machine it was not working. Finally it was identified as a
missing module module-device-manager with arg do_routing=1.
Once it was loaded everything was fine. This particular module was not shown in the pulse configurations. So I have to find that and load,
pacmd
load-module module-device-manager do_routing=1
One can add a line in the default configuration file available in /etc/pulse.or one can add it in the user configuration file also.Now to make the new bluetooth speaker being used to play sound. For that issue the command 'move-sink-input ' using pacmd. You can find the sink names my issuing the command 'list-sinks'.
If your speaker is not connecting, it may be that it is already connected elsewhere. If it is not so, remove-device; scan on; pair; and connect using bluetoothctl. I was worrying how to make file transfer using bluetooth (Bluez5). Actually very little information is available in LFS documention or in general in the NET. This very true and unfortunate about Bluez in general. They do not provide any real user doc or nothing is available in net. So the steps are as follows:
You need to install OBEX library. Then you build Bluez5 (if it not done already). It will install obexd. After installation you can find obexd in $PREFIX/libexec/bluetooth/obexd.This is where you find bluetoothd also. One generally makes a link for bluetoothd in /usr/sbin. A similar link can be made for obexd also. Once you start bluetoothd and obexd you can find object transfer profiles in bluetoothctl->show.If you need a phone to push objects to the computer, you need to run obexd with options '-a' and '-r '. if '-a' is not given phone will fail to send the file. Now how to push a file from Computer to Phone. For this you need obexctl, I do not think it is a finished tool, and it will not be installed while we build Bluez 5. I have seen it in the source tree and copied to /usr/bin/. It should be used to connect the Phone and when the connection is established one can 'send ' and you have to accept the request in the phone.
Starting obexd as a deamon was a problem. When obexd was tried on a text terminal (init 3) it was not possible to start since it needs a dbus session which in turn needs X display. It means one need to login an X seession before you start obexd. If you dissable X while building DBUS (--without-x) then Window Managers will not work. But there is solution with 'dus-run-session < command> [args]'. That means you can start a service obexd (like bluetoothd) in the system start-up. So just by switching on the Computer ( if pairing, trusting etc... was done earlier) one can push files from Phone to computer.
>> connect <device>
Second time onwards just connection is fine. Probably you can trust the device.
>> trust <device>
I am a beginner and I want to understand some basics of Client-Server applications written in C (I understand web based server-client applications written in Java, PHP ,etc).
To be more specific, I am talking about ZABBIX which is a client-server tool (Zabbix_server is a server and zabbix_agentd is a client, both written in C).
Zabbix_server asks zabbix_agentd for data and zabbix_agents responds accordingly.
I have imported zabbix codes on Eclipse and have tried to debug to understand codes. A complete execution of zabbix_agentd on Eclipse just launched the daemon successfully and created a child process. But when I check the log, I find that different functions are being called which had not come in the way while debugging. It means, these functions are called by some process, may be inetd, etc. (correct me if i am wrong). I tried to find inetd on RHEL 6.4 OS, but it was no where found (using "service inetd status", "find").
So, how those functions are being called? Can anyone please give me ideas about that?
Please suggest me how to use those calling requests to further debug my client application.
One thing I have noticed while debugging Eclipse is that, I get below error after calling fork():
No source available for "fork() at 0x36ca0acbc0"
I couldn't understand the impact of the above error as the daemon keeps on working after this error also.
I browsed through similar error different people getting and found that their binaries were not linked to sources. However, my binaries are linked to sources also. I mean, expanding the binary of zabbix_agentd shows several *.h and *.c files.
As this error terminates the debugger immediately but the line of code at this occurrence is the last line of the source file also. So, I cannot say if I need to take care for this error.
Is this error the reason why I am not able to view other functions being called?
Please let me know if more information is required.
Thanks in advance.
Regards,
Rohit
I have an exam on tomorrow on TCP/IP programming. Following is one of the previous question on this paper.
Write and run a client and a server program. Using C language in UNIX, with the
following specifications :
• A TCP client program will send a range of number (e.g. 1 to 10) to the server.
• TCP server accept the number range from client and send back the sum of the
number range. Client will print the result.
I dont know how to setup the compiler and other settings to run this tcp ip programs. When I search online, I got two different programs, one for Client and another For server. Some please tell me how can i run these programs to get desired output. What kind of compiler should I install on my system.( I am using windows 7) ??
Since the assignment requires your code to work on a Unix system, you first need to install one. Follow these simple steps to install a virtual Unix environment on top of your existing Windows installation.
Download and install VirtualBox for Windows.
Download & unpack this Ubuntu 12.10 disc image (NOTE: Requires 7-Zip).
Launch VirtualBox and create a new Virtual Machine (name it Ubuntu).
In the "Virtual Hard Disk" settings, select "Use existing hard disk" and select the image file you just downloaded (NOTE: It's filename should end in ".vdi").
Run your new Virtual Machine. You should see the Ubuntu splash screen.
Login with username ubuntu and password reverse (NOTE: Case Sensitive!).
Open up Terminal and type sudo apt-get install build-essential (NOTE: when Terminal prompts you for a password, use reverse).
You should (with hope) have everything you need for your assignment. For more information on network programming, consult Beej's Guide to Network Programming -- Using Internet Sockets.
You need to open two different terminals on your system.
In the first terminal compile and run the server.c program.(make sure either you listen to all ips or your host ip(atleast).
while this is running.(it will wait for a request from your client program)
Run the client program in the other terminal.
Hope this solves the problem!
For details on how to create and run a file in unix refer http://www.wikihow.com/Compile-a-C-Program-Using-the-GNU-Compiler-%28GCC%29
P.S: you can do the same in win7 if iam not wrong only that terminal here in called command prompt!
Post the results if possible!
Download a thing called VMWare player. And look for a Ubuntu image that you can load with the VMWare player. That way, you will have a little Linux virtual machine that you can run inside or along with Windows 7. You can use the compiler GCC in your Ubuntu or whatever other Linux virtual machine. And get lots of coffee. Blargle is correct, but I think my suggestion is a little better, because you end up having a fairly complete Unix type environment to develop in. Blargle's way put Unix tools on top of Windows, which I find to be kind of clunky.
I learnt socket programming from this site. He has given everything in detail . Download an Vmware workstation and load up ubuntu . Understand the programs they are pretty much straight forward .
Maybe you can try to look at Network Socket on the web. You can easily find a lot of good tutorial that can answer your question.
You can use the compiler you want on your system, depending on what are you using now.
I cannot fix this without asking for help. On install of LAMP via Syn. Pkg. Mgr. and trying to setup and run LAMP, I have received:
mark#Lexington:/$ apachectl restart
/usr/sbin/apachectl: 87: ulimit: error setting limit (Operation not permitted)
apache2: Syntax error on line 237 of /etc/apache2/apache2.conf: Syntax error on line 1 of /etc/apache2/sites-enabled/example.com: /etc/apache2/sites-enabled/example.com:1: <VirtualHost> was not closed.
The /etc/apache2/apache2.conf file talks about a <VirtualHost> and I have read examples of what to put there, but I'm not able to understand what I am doing. And since the file says DON'T unless you know what you are doing, I am asking:
This is XUbuntu 12.04. I tried installing LAMP. The purpose of this is to run vnstat in a browser and see the bandwidth usage. Also, I want to "serve" a mp3 file to a weblog I keep. I don't understand why I would make an Apache error log visible in a browser. I would have little reason to see the bandwidth usage at another location. The only other reason for LAMP is I am trying to use MythTV to send the TV signal to a "smart" tv via ethernet cable.
If you can point me towards a URL or other help, I'm much obliged.
If you can give me the name of a text editor that shows line numbers so I can look at "line 237" I'll try to figure the syntax error.
oh, this looks easy...i think. You'll see <VirtualHosts> near or at the top of the file /etc/apache2/sites-enabled/example.com (error says line 1). Scroll down through everything. if you do not see </VirtualHosts> (notice the slash), put that in the bottom of the file. Save and close, then restart apache
Regarding the "operation not permitted": you may have to use sudo to elevate your privileges (assuming you are on unix, which i think you are). Research how to do this if you don't know.