After installation of new CentOS 8 on VM device I was surprised to find that secure shell daemon is configured differently than I saw in previous versions of CentOS devices. CentOS 8 SSH Daemon does not use definition of Ciphers, KexAlgorithms, GSSAPIKexAlgorithms and MACs from /etc/ssh/sshd_config file anymore as for example CentOS 7 does, but… Read More »
The total idea of encryption is simple to convert readable data into meaningless gibberish using unpredictable math algorithm. However encryption by itself is useless without decryption because the person for whom these data are intended must be able to read them. In other words he/she must be able to convert data back in readable format.… Read More »
Valgrind is a powerful programming tool for memory profiling, memory leak detection. Also it can be used for thread error analysis and profile programs in detail. Valgrind instrumentation framework permits to build new tools. Valgrind is available for many Unix based operating systems. Here is an example how to detect memory leak in simple c++… Read More »
The db_dump utility dump Berkeley DB databases into a flat-text representation. Berkeley DB distribution includes source code of db_dump utility and also other useful utilities such as: db_archive, db_checkpoint, b_deadlock, b_dump185, db_load, db_printlog, db_recover, db_stat, db_upgrade and db_verify. All these utilities may be used for database debugging and maintenance. Here is example of Makefile for… Read More »
Remmina is free remote desktop client for GNOME desktop environment. It supports different types of remote control for many Linux versions. Remmina is able to display and control a desktop on remote computer. Especially it is possible to use Remmina for Windows Remote Desktop sessions. I found that latest Ubuntu iso destrutions (Ubuntu 16-64 and… Read More »
Usually such tools as telnet, nmap or nc are used to find listening remote ports. However nmap and netcat are not included in default Linux installation, telnet is good for manual testing and is not friendly for scripting task. So sometime I am using cURL or wget to get information about open ports on remote… Read More »
Network discovery is a process to find other computers and devices on some network and to get obtainable information about them. The discovery procedure is based on sending out request messages over and analyzing responses from remote devices. ICMP (Internet Control Message Protocol) is most frequently method detect remote device. Below is presented simple Linux… Read More »
I needed to install gdb quickly on my CentOS 7 VM box, but it failed. yum command could not find appropriate repository for download and installation. The same I had before with different application. Of course it was possible to perform all installation steps manually: find location of appropriate rpm or source files and rebuild,… Read More »
Public and private key pair is alternative way of server logging using Secure Shell (SSH) protocol. It gives possibility to avoid user name and password prompts so could be faster and more comfortable. Besides both keys represent two long string of characters, so eventually it is more difficult to crack. There are a lot of… Read More »
SSH tunneling is a technique to transfer arbitrary networking data using an encrypted SSH connection. It can be used to add encryption to not secure protocols such as HTTP and to bypassing firewalls. It is also named as port forwarding, there is a post related to C# implementation of SSH port forwarding. Here is presented… Read More »