how to debug application as root in eclipse in Ubuntu? - c

I'm programming application using libpcap. when I debug the application in normal mode, pcap cannot get the network device. it seems that I have to debug the application in root.
How can I debug the application in root? I have the root password.
I think eclipse has such an option that can add root for the debugging application,but I don't know how to do it.
please help.

Enable your user to run gdb as root without being asked for any
password:
sudo visudo
Add the following line after all other rules:
<youruser> ALL=(root) NOPASSWD:/usr/bin/gdb
Create or modify a debug configuration in eclipse to run gdb as root
e.g. in Run > Debug Configurations > C/C++ Application > YourProject Debug:
change Debugger > Main > GDB debugger from gdb to sudo -u <youruser> gdb
Update (and warning!):
In his comment nategoose pointed out that this answer should come with a warning:
Enabling a user to use sudo for gdb like suggested in my answer in fact gives admin privileges to him/her which in many cases might be an undesired side effect. I therefore consider the answer appropriate in an environment where it's not assumed that the user would try to harm the system (e.g. it's your own personal computer or a virtual machine)
For a multi-(non-trusted)-user environment I think it might be a better idead to utilize unix' file capabilities to enable gdb to debug an application without the need of admin privileges

You can use gdbserver on localhost to attach a existing process, the following is the command line:
sudo gdbserver :<listening port> --attach <pid>
Or you can create a new process using gdbserver:
sudo gdbserver :<listening port> <process executable>
Then you can create a debugging configuration in Eclipse, in the debugger tab, the debugger item, select gdbserver, and input the listening port in the connection tab in the bellow.

Launch Eclipse with sudo (just for completeness: http://www.eclipse.org/forums/index.php?t=msg&goto=516838&)
Update: Follow xmoex solution. If you run Eclipse as root (ie. using sudo) your files will be root-owned... which you probably don't want.

Another solution is to grant you (or the gdb executable) the rights to make some pcap captures as mentioned here. With something like this :
setcap cap_net_raw,cap_net_admin=eip /usr/bin/gdb
you should be able to allow to capture packets to gdb without being root.

Here's how I did it:
Create a C/C++ Remote Application
On the target, make sure your sudo does not prompt for a PW
Look at Debug Configurations → Debugger → Port number
Edit Debug Configurations → Main → Commands to execute before application
Change to:
sudo gdbserver :<port number> <path to application>;exit #
This will basically run the gdbserver that would normally be executed by eclipse inside the sudo, the trailing '#' will keep the eclipse command from executing.

this question was asked a long time ago but if this will help to anybody I open a bug in bugzilla and this short thread solved the problem:
bugzilla bug

From the console in the directory with your executable:
sudo gdb ./my_program
If eclipse supports remote debugging then you could do that even though it is running locally.
From the console:
sudo gdbserver localhost:<port_number> ./my_program
And then tell Eclipse the address (localhost and the port number you chose).
Oh yeah, you said the reason you were doing this was because you were using libpcap, so you may not want to use remote debugging over TCP because you may end up capturing your debugging connection packets in addition to your other network traffic.
In that case you do your remote (but really local) debugging over a serial port. I have never done this on a local machine, but you could use two actual serial ports (attaching them though a null modem) or try using a psudoterminal:
sudo gdbserver /dev/ptmx ./my_program
This will create the psudo-terminal under /dev/pts/ but you'll have to figure out the name of it, and it might also create it with restrictive permissions. You can get around those. Unless you are running lots of terminal windows as root, it is not likely that you have many entries under /dev/pts that belong to root, so take note of the one that does after running the above command and then sudo chmod or sudo chown it to make it usable for your normal user and then tell your debugger to use that as your serial connection to your remote debugging target.

easiest way, try sudo ./eclipse, then debug as usual

Related

Deactivate macport

I am trying to install the macport demeter using the following line in mac terminal:
sudo port install demeter
I get the error message
Error: Failed to activate demeter: Image error: /opt/local/lib/perl5/vendor_perl/5.34/darwin-thread-multi-2level/Ifeffit.pm is being used by the active p5.34-ifeffit port. Please deactivate this port first, or use 'port -f activate demeter' to force the activation.
I have two questions:
(1) Why am I getting this error message? Have I accidentally got two copies of demeter?
(2) How can I deactivate this port? (I'd rather deactivate it then use the force activate option)
When I run
sudo lsof -i -n -P | grep TCP
I can't actually see 'p5.34-ifeffit port' in the list of ports.
This is a bug in the demeter port. It should not install the files of the ifeffit perl module, but instead declare a dependency on p5.34-ifeffit.
Please file a ticket at https://trac.macports.org/newticket.
You can force the activation, but that will overwrite the file(s) in question with the copies from the demeter port. Uninstalling that port later will delete those files, which may then in turn break other software that relies on p5.34-ifeffit.
I'm not experienced with Demeter but you might try asking for help on the MacPorts users mailing list:
https://lists.macports.org/mailman/listinfo/macports-users
Or raise a ticket on the MacPorts Trac system:
https://trac.macports.org/newticket?port=demeter
Craig

How edit files with Visual Code remote extension using sudo

The Visual Code remote SSH extension allows editing any remote file in the embedded terminal just using code <filename> which is super useful.
However when opening a file with sudo e.g. sudo code /etc/fstabs it returns
sudo: code: command not found
Is there any way to allow the use of code to any user?
I don't believe this is possible at the time of writing as it would require the underlying node which is running VSCode server to be running with sudo, which it is not.
I have opened a GitHub Issue here.

How do i resolve "Failed to parse remote port from server"

I'm setting up a new remote host and every time i initiate it i get the following error output: Any feedback or direction on how to resolve this issue?
Pseudo-terminal will not be allocated because stdin is not a terminal.
Linux Destiny 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1 (2019-04-12) x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
mesg: ttyname failed: Inappropriate ioctl for device
bash: cannot set terminal process group (3202): Inappropriate ioctl for device
bash: no job control in this shell
mesg: ttyname failed: Inappropriate ioctl for device
Installing...
Downloading with wget
WARNING: tar exited with non-0 exit code
Found running server...
*
* Reminder: You may only use this software with Visual Studio family products,
* as described in the license (https://go.microsoft.com/fwlink/?linkid=2077057)
*
cat: /root/.vscode-remote/.473af338e1bd9ad4d9853933da1cd9d5d9e07dc9.log: No such
file or directory
Server did not start successfully. Full server log:
cat: /root/.vscode-remote/.X.log51ec4692-
4da4-4ec0-b613-5a3563034cf1====
: No such file or directory
"install" terminal command done
Received install output: : No such file or directory
Failed to parse remote port from server output: : No such file or directory
If the server fails to shut down properly, sometimes it leaves dangling lockfiles. This can cause startup to fail and produce the "Failed to parse remote port from server output" error message. In this case the solution is to simply to delete the lockfiles:
.vscode-server/bin/[:xdigit:]*/vscode-remote-lock.*
Fixed the issue. It appears I had 2 other server agents running incorrectly. I killed both server agents using kill (PID) and removed ".vscode_remote" directory from user home directory. Then i reinitialized remote-ssh from vscode. Successfully connected!
On remote machine you do not have a tar installed. It's in log output
Installing... Downloading with wget
WARNING: tar exited with non-0 exit code
so under a root run:
apt-get install tar
or with sudo, if you have a user with sudoers configured:
sudo apt-get install tar
I also got the same issue and my workaround was to provide proper rights to the home or user folder, so vscode can create a remote folder and do the required installation on it.
Example :
sudo chmod -R 777 home/
In this case, I have provided all rights to my home folder and It worked like a charm for all the users.
I ssh'd onto the remote server (linux) and then deleted both directories as follows:
$ rm -r .vscode-server.backup2022-04-03T16:20:18-05:00
$ rm -r .vscode-server
In case someone else encounters the same issue - I had an instance where remote target had no space left on device. After extending root volume of target machine, connection worked fine.
I had the same issue because vscode was looking for my .vscode-server directory in the wrong location (it was in a custom location due to restrictions on where files can be saved). This can be fixed by using How to change vscode-server directory. Specifically add:
"remote.SSH.lockfilesInTmp": true,
"remote.SSH.serverInstallPath":{
"hostname":"/path/to/.vscode-server/.."
}
To your settings.json
In my case, it wasn't working because of server asking for new password when starting a session. What I did was to open a new default terminal (not VSC terminal but your OS default terminal like ZSH, CMD, and so on). And I used the ssh command to login. I logged in successfully and changed the password. Then I tried connecting with the new password and it worked because the server didn't asked for password change now.
Command:
ssh username#IP
Enter password and you'll get asked to change the password. Change the password and try connecting again with new password using SSH VSC extension.
If yout authorize by ssh-key - also check the value of User parameter in VsCode ssh config. User must have matching key in ~/.ssh/authorized_keys on remote host.
#Sachin's answer directed me in the right direction, VSCode needs permissions in order to create some files, but instead of giving 777 permissions to your home folder (which can be dangerous) you can just chown the user that wants to log in (the user for me was ubuntu):
sudo chown -R ubuntu /home
I also got the same issue and my workaround was to provide proper rights to the home or user folder, so vscode can create a remote folder and do the required installation on it.
Step 1: Add port to your config file :
Host hostname
Port 22
User username
Step 2 : Go to File->Prefrences ->Open settings.json fle
Search for lockfilesInTmp
and check the box next to that

Compile for Chromebook using Crouton

I currently have an Asus c300 chromebook. Since it doesn't have legacy boot, I'm using crouton to get a more standard command line environment. I was able to install gcc very easily in the chroot environment. It works very well under chroot.
Since the underlying hardware is the same, I thought the resulting executable should work for chromebook, without me being in the chroot environment. If true, I thought I could go into the chroot environment, compile whatever program I want/need, and exit back out to the regular environment and use it.
I tried it with a simple hello world program. When I tried to run the executable, I got the following error:
bash: ./a.out: Permission denied.
I tried to run it with sudo, and I get a similar error:
sudo: unable to execute ./a.out: Permission denied.
I even used su to login as root, and I still could not run the program (got the first error).
I thought su/sudo would override any kind of permission restriction. But, it's apparently not the case on the chromebook.
What am I missing? Is what I want to do possible?
EDIT: File permission was already set to 777.
You might simply have to change the permissions of the file or check the files ownership. umask determines weather or not a file that is created gets execute permissions by default. What does -ls -lat on the file reveal?
Also try running
chmod +x ./a.out
You can find more details of error with strace command
use:
strace ./a.out and check output.
I suppose you have different env (path and LD_library_path) under the chroot.

Error : Port gnuplot not found

I have just installed macports as per the instruction given on their website. But as i type
sudo port install gnuplot
i get an error
Error: Port gnuplot not found
also for self update i get
Error: Error synchronizing MacPorts sources: command execution failed
Please run `port -v selfupdate' for details.
Error: /opt/local/bin/port: port selfupdate failed: Error synchronizing
MacPorts sources: command execution failed
It is same for any software i am trying to download using macport. How to solve this issue?
Is it because my college firewall is blocking downloads using macport? Which port do macport use to download?
And also if they are blocking it how come linux users can download using yum, apt-get etc
You can run sudo port -d selfupdate to see why the update fails. I'm assuming it's because your local network blocks outbound access to port 873 (rsync), which MacPorts uses for updating. You should really ask your network administrator to allow outbound rsync – there's really no danger whatsoever associated with it.
To my knowledge, MacPorts is the only package manager, which uses the rsync protocol, so that explains why yum, apt-get and others work fine.
The synchronization failure also explains why the gnuplot port doesn't exist for you. MacPorts needs a file that tells it how to get and build gnuplot, which it downloads using rsync. If that never worked for you, you don't have the file and hence MacPorts assumes there is no gnuplot port.
If your network administrators refuse to open the rsync port (for whatever reason), there's an FAQ entry to work around that, as well: http://trac.macports.org/wiki/FAQ#selfupdatefails.

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