How to use the command 'extrace' (with examples)
- Linux
- December 17, 2024
’extrace’ is a command-line utility designed primarily for tracing and logging program executions within a system. By capturing calls to exec(), it provides valuable insights into how and when various processes are run. This can be particularly useful for system administrators, developers, or security professionals who need to monitor the activities occurring on a system, debug their applications, or ensure security policies are adhered to.
Use case 1: Trace all program executions occurring on the system
Code:
sudo extrace
Motivation:
Tracing every program execution on a system can be instrumental for numerous reasons, including security auditing, performance monitoring, and debugging. By getting a comprehensive view of all executed processes, administrators can spot unauthorized executions, analyze system behavior under load, or verify that specific processes are running as expected.
Explanation:
sudo
: Grants the necessary administrative privileges required to trace all executions system-wide since this requires access to processes across different users.extrace
: Invokes the extrace command itself, which monitors exec() calls throughout the system.
Example output:
1582 /usr/bin/python3
1583 /bin/bash
1584 /usr/bin/vim
This output shows a simple sequential list of processes started on the system, with each line indicating the process ID and the path of the binary being executed.
Use case 2: Run a command and only trace descendants of this command
Code:
sudo extrace command
Motivation:
In scenarios where you are only interested in the child processes of a particular command, rather than all system processes, this use case shines. It’s particularly useful during application testing or when troubleshooting a specific service to identify what additional processes are spawned during its execution.
Explanation:
sudo
: Often required for commands that need elevated permissions to accurately trace all child processes.extrace
: Initiates the tool itself.command
: A placeholder for any specific command whose child processes need to be traced. It limits the scope of extrace’s monitoring to only those processes directly related to the initiated command.
Example output:
2001 /bin/bash
2002 /usr/bin/apt-get update
2003 /usr/bin/dpkg
The output demonstrates processes spawned by, for example, a bash
script, which itself initiated an apt-get update
command, further calling dpkg
.
Use case 3: Print the current working directory of each process
Code:
sudo extrace -d
Motivation:
Understanding the context in which a process is initiated, including its directory origin, can be crucial during debugging or forensic analysis. Knowing the working directories helps pinpoint configuration issues or unauthorized activities especially when file paths are relevant to the operation of processes.
Explanation:
sudo
: Needed to ensure full access to information on all processes.extrace -d
: The-d
option instructs extrace to include the current working directory (CWD) for each logged exec() call.
Example output:
2563 /usr/bin/python3 /home/user/scripts
2564 /bin/ls /var/log
Here, each execution record includes the process ID, the path of the binary, and the current working directory where the execution was started, giving an added context to each process’s action.
Use case 4: Resolve the full path of each executable
Code:
sudo extrace -l
Motivation:
In systems with complex PATH environments or symbolic links, it’s often necessary to confirm the exact executable being called. Resolving full paths prevents ambiguities and ensures correct binaries are being executed, reducing troubleshooting efforts in deployments or routine checks.
Explanation:
sudo
: Elevated permissions are typically necessary for precise path resolution across all system activities.extrace -l
: The-l
flag tells extrace to resolve and display the absolute path of each executable.
Example output:
3576 /usr/local/bin/python3
3577 /usr/sbin/nginx
Outputs show complete paths to the executed programs, confirming which specific binaries are being used, which can be critical for security or debugging purposes.
Use case 5: Display the user running each process
Code:
sudo extrace -u
Motivation:
In multi-user environments, knowing who initiated a particular process can help in tracking user activities, ensuring accountability, and identifying potential insider threats. Identifying which user executes certain commands ensures processes are run under the intended privilege level, preventing unauthorized privilege escalation.
Explanation:
sudo
: Provides the required access to gather user information for all process executions.extrace -u
: The-u
option specifies that the output should include user identifiers for each process.
Example output:
root 3780 /usr/sbin/apache2
user1 3781 /home/user/scripts/firefox
This gives insight into which user initiated each process, highlighting operational use or possible misuse of system resources.
Conclusion:
The ’extrace’ command, with its tailored options, allows extensive insight into process executions on a system. Whether for complete system monitoring or focused, conditional tracing, each use case provides unique benefits. From auditing and debugging to automation optimization and security enforcement, ’extrace’ offers versatile capabilities that should be a staple in the toolbox of administrators and developers seeking to maintain a robust and well-monitored computing environment.