sys

3 posts with the tag “sys”

How to resolve openssl error when loading shared libraries libssl.so.1.1

Jan 15, 2025

Cowrie

Dev @ Bswen

1. The purpose of this post

After install openssl, we run the below command:

openssl version

to verity the installation, but sometimes we would get this error:

[root@node1 openssl-1.1.0f]# openssl version
openssl: error while loading shared libraries: libssl.so.1.1: cannot open shared object file: No such file or directory

2. Environments

The linux system is:

[root@node1 openssl-1.0.0f]# uname -a
Linux node1 3.10.0-862.14.4.el7.x86_64 #1 SMP Wed Sep 26 15:12:11 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

3. Debug

We try to find the file named libssl.so.1.1 as follows:

[root@localhost openssl-1.1.0f]# ll /usr/lib64/libssl*
-rwxr-xr-x. 1 root root 315096 8m   7 2017 /usr/lib64/libssl3.so
lrwxrwxrwx. 1 root root     16 7m   9 2009 /usr/lib64/libssl.so.10 -> libssl.so.1.0.2k
-rwxr-xr-x. 1 root root 470336 8m   4 2017 /usr/lib64/libssl.so.1.0.2k
[root@localhost openssl-1.1.0f]# ll /usr/local/lib64
Total 8984
drwxr-xr-x. 2 root root      39 11m  8 11:30 engines-1.1
-rw-r--r--. 1 root root 4967326 11m  8 11:30 libcrypto.a
lrwxrwxrwx. 1 root root      16 11m  8 11:30 libcrypto.so -> libcrypto.so.1.1
-rwxr-xr-x. 1 root root 2934272 11m  8 11:30 libcrypto.so.1.1
-rw-r--r--. 1 root root  766182 11m  8 11:30 libssl.a
lrwxrwxrwx. 1 root root      13 11m  8 11:30 libssl.so -> libssl.so.1.1
-rwxr-xr-x. 1 root root  521384 11m  8 11:30 libssl.so.1.1
drwxr-xr-x. 2 root root      61 11m  8 11:22 pkgconfig

We can find that the libcrypto.so.1.1 is located in the /usr/local/lib64, But openssl try to find the .so libraries in the LD_LIBRARY_PATH:

[root@localhost ~]# echo $LD_LIBRARY_PATH
/usr/lib64:/usr/local/lib64

So the solution is try to tell openssl where the library is.

4. Resolve it

There are two methods to resolve this problem:

4.1 Method 1: Change the LD_LIBRARY_PATH

export LD_LIBRARY_PATH = /usr/local/lib64:$LD_LIBRARY_PATH

LD_LIBRARY_PATH

LD_LIBRARY_PATH is an environment variable in Linux and other Unix-like operating systems. It specifies a list of directories where the dynamic linker (ld.so or ld-linux.so) should look for shared libraries before searching the standard library paths (like /lib and /usr/lib).

Purpose When you run a program that depends on shared libraries, the dynamic linker uses LD_LIBRARY_PATH to locate the necessary libraries if they aren’t in the default locations. This is especially useful for:

• Running applications that use custom or non-standard library versions.
• Testing new libraries without overwriting system-wide libraries.
• Developing and debugging software.

4.2 Method 2: Create a link to the file

[root@localhost openssl-1.1.0f]# ln -s /usr/local/lib64/libssl.so.1.1 /usr/lib64/libssl.so.1.1
[root@localhost openssl-1.1.0f]# ln -s /usr/local/lib64/libcrypto.so.1.1 /usr/lib64/libcrypto.so.1.1

5. More about the LD_LIBRARY_PATH

As the linux documents shown:

More about the LD_LIBRARY_PATH

You can temporarily substitute a different library for this particular execution. In Linux, the environment variable LD_LIBRARY_PATH is a colon-separated set of directories where libraries should be searched for first, before the standard set of directories; this is useful when debugging a new library or using a nonstandard library for special purposes. The environment variable LD_PRELOAD lists shared libraries with functions that override the standard set, just as /etc/ld.so.preload does. These are implemented by the loader /lib/ld-linux.so. I should note that, while LD_LIBRARY_PATH works on many Unix-like systems, it doesn’t work on all; for example, this functionality is available on HP-UX but as the environment variable SHLIB_PATH, and on AIX this functionality is through the variable LIBPATH (with the same syntax, a colon-separated list).

LD_LIBRARY_PATH is handy for development and testing, but shouldn’t be modified by an installation process for normal use by normal users; see “Why LD_LIBRARY_PATH is Bad” at http://www.visi.com/~barr/ldpath.html for an explanation of why. But it’s still useful for development or testing, and for working around problems that can’t be worked around otherwise. If you don’t want to set the LD_LIBRARY_PATH environment variable, on Linux you can even invoke the program loader directly and pass it arguments. For example, the following will use the given PATH instead of the content of the environment variable LD_LIBRARY_PATH, and run the given executable:

  /lib/ld-linux.so.2 --library-path PATH EXECUTABLE

Just executing ld-linux.so without arguments will give you more help on using this, but again, don’t use this for normal use - these are all intended for debugging.

Final Words + More Resources

My intention with this article was to help others who might be considering solving such a problem. So I hope that’s been the case here. If you still have any questions, don’t hesitate to ask me by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

• 👨‍💻 Linux shared libraries documents
• 👨‍💻 LIBRARY_PATH vs LD_LIBRARY_PATH
• 👨‍💻 the full linux shared libary documents

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

Tags:

• sys

How to install wrk on linux system?

Jan 1, 2025

Cowrie

Dev @ Bswen

1. Purpose

In this post, I will demo how to install wrk, a web url performance test tool on linux/unix/mac systems.

What is wrk test tool

WRK is a modern HTTP benchmarking tool designed to measure the performance of web servers. It is similar to older tools like ab (ApacheBench) or siege, but it comes with some additional features that make it more powerful and flexible.

WRK is typically used to:

• Benchmark the performance of web servers.
• Test the scalability of web applications under load.

2. The solution

2.1 How to install wrk?

On linux systems, to ensures that your package manager (APT) has the most up-to-date information about available packages, versions, and dependencies, we should update the local cache first:

root@launch-advisor-20191120:/etc/nginx# apt update
....

Then we install the wrk tool using apt install command:

root@launch-advisor-20191120:/etc/nginx# apt install wrk
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package wrk

You can see that we got an error E: Unable to locate package wrk, why?

Why we got Unable to locate package wrk error

The error you’re encountering happens because the wrk package is not available in the default repositories of your system’s package manager (apt). The wrk tool, a modern HTTP benchmarking tool, is not typically included in the default Ubuntu/Debian repositories.

And wrk can only run on Unix-like systems. Such as linux, mac, solaris, etc. It can only be compiled on these systems.

So we can install it from source:

Download wrk source code:

sudo apt-get install build-essential libssl-dev git -y
git clone https://github.com/wg/wrk.git wrk

Then build it:

cd wrk
sudo make

Then we can use the binary:

# move the wrk executable to your PATH
sudo cp wrk /usr/local/bin

2.2 Verify the installation of wrk

root@launch-advisor-20191120:~/wrk# wrk
Usage: wrk <options> <url>
  Options:
    -c, --connections <N>  Connections to keep open
    -d, --duration    <T>  Duration of test
    -t, --threads     <N>  Number of threads to use

    -s, --script      <S>  Load Lua script file
    -H, --header      <H>  Add header to request
        --latency          Print latency statistics
        --timeout     <T>  Socket/request timeout
    -v, --version          Print version details

  Numeric arguments may include a SI unit (1k, 1M, 1G)
  Time arguments may include a time unit (2s, 2m, 2h)
root@launch-advisor-20191120:~/wrk#

It works.

3. Summary

In this post, I demonstrated how to install wrk , a great performance test tool . That’s it, thanks for your reading.

Final Words + More Resources

My intention with this article was to help others who might be considering solving such a problem. So I hope that’s been the case here. If you still have any questions, don’t hesitate to ask me by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

• 👨‍💻 wg/wrk: Modern HTTP benchmarking tool

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

Tags:

• sys
• wrk

How to solve 'BPF' object has no attribute 'get_syscall_fnname'?

Dec 31, 2024

Cowrie

Dev @ Bswen

This post will show you how to solve ‘BPF’ object has no attribute ‘get_syscall_fnname’ when run bpf program in linux ?

What is BPF program?

A Linux BPF (Berkeley Packet Filter) program is a type of code that can be executed in the kernel space of the Linux operating system. BPF programs are used for a variety of tasks, including network packet filtering, performance monitoring, and security enforcement. They are highly efficient and can be dynamically loaded into the kernel without the need for recompilation or rebooting.

Problem

When you run a python bpf_program in linux, you run this command:

For example, if our bpf program’s name is example.py:

python example.py

The example.py content is:

example.py

from bcc import BPF

bpf_source = """
#include <uapi/linux/ptrace.h>

int do_sys_execve(struct pt_regs *ctx) {
  char comm[16];
  bpf_get_current_comm(&comm, sizeof(comm));
  bpf_trace_printk("executing program: %s\\n", comm);
  return 0;
}
"""

bpf = BPF(text=bpf_source)
execve_function = bpf.get_syscall_fnname("execve")
bpf.attach_kprobe(event=execve_function, fn_name="do_sys_execve")
bpf.trace_print()

You get this error:

root@launch:~/linux-observability-with-bpf/code/chapter-4/kprobes# python example.py
Traceback (most recent call last):
  File "example.py", line 15, in <module>
    execve_function = bpf.get_syscall_fnname("execve")
AttributeError: 'BPF' object has no attribute 'get_syscall_fnname'

The error AttributeError: 'BPF' object has no attribute 'get_syscall_fnname' indicates that the BPF class from the bcc module does not have a method named get_syscall_fnname.

Environment

You check your os version by this command:

root@launch:~# cat /etc/os-release

NAME="Ubuntu"
VERSION="16.04.6 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.6 LTS"

Python version:

Python 2.7.17 (default, Apr 15 2020, 17:20:14)
[GCC 7.5.0] on linux2

Solution: Install the bcc dependencies

According to python bcc documents, you should install the libbcc and python bcc into system.

# add key server
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D4284CDD
# add iovisor to repo
echo "deb https://repo.iovisor.org/apt/bionic bionic main" | sudo tee /etc/apt/sources.list.d/iovisor.list
# update the repo
sudo apt-get update
# install libbcc
sudo apt-get install libbcc
# install python-bcc
sudo apt-get install python-bcc

what is libbcc?

libbcc

libbcc is a library that is part of the BPF Compiler Collection (BCC). BCC is a set of tools and libraries for creating efficient kernel tracing and manipulation programs using BPF (Berkeley Packet Filter). libbcc provides a high-level framework for writing BPF programs in C and Python, and it includes various utilities for loading, compiling, and interacting with BPF programs.

In summary, libbcc is essential for developing and running BPF-based tools and applications on Linux systems.

and what is python-bcc:

python-bcc

python-bcc is a Python binding for the BPF Compiler Collection (BCC). It allows you to write and run BPF programs using Python. python-bcc provides a high-level interface to interact with BPF programs, making it easier to develop and deploy BPF-based tools and applications in Python.

In summary, python-bcc enables Python developers to leverage the power of BPF for tasks such as system tracing, monitoring, and performance analysis on Linux systems.

After all done, you can run the python bpf script again:

root@launch:~/linux-observability-with-bpf/code/chapter-4/kprobes# python example.py
            bash-12522 [001] .... 330817.825407: 0x00000001: executing program: bash

It works!

Final Words + More Resources

My intention with this article was to help others who might be considering solving such problem. So I hope that’s been the case here. If you still have any questions, don’t hesitate to ask me by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

• 👨‍💻 Python bpf library: bcc
• 👨‍💻 bcc Python Developer Tutorial

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

Tags:

• python
• sys