Category Archives: networking

Agentless remote monitoring with SNMP and WMI

The previous article “Remote Monitoring System with Minimum Coding” presents an example how to monitor processes on Linux systems using simple bash script and upload result to the remote HTTP server. Linux cron service should schedule script execution on a repetitive basis. The bash script plays role of monitoring agent which collects required information and… Read More »

Raw sockets.

Approximately year ago I wrote an article “Wiresharking TCP Split Handshake Attack“. Normally client/server application written on socket level does not permit to split handshaking. For example TCP client connect function initiates a connection on a socket and performs all 3 handshaking step. Handshaking process is hidden in Transport layer of ISO model. To manipulate… Read More »

ssl_error_protocol_version_alert in Wireshark or weak security protocol on the client side

I cannot connect to my site from my old Ubuntu 12.0 virtual machine. Instead of blog content the Firefox shows ssl_error_protocol_version_alert error. It means that browser does not support TLS protocol version that server requires. According to supports only TLS 1.2 and TLS 1.3 protocols. But Firefox browser users only SSL 3.0… Read More »

Decrypting TLS data with Wireshark on Mac

This post is about how decrypt TLS data with Wireshark using session key file. The session key file saves combination of secret keys which web browser used to encrypt or decrypt http traffic. Not all browsers may save session key, as I know only Google Chrome and Firefox permit to do this. The example below… Read More »

Create private backup of your web site

Everything may happen, but being wise after the event sometime is not a good choice. On Saturday 28 August 2021 incident happened the data on servers of my Webhosting provider were wiped, some backups were destroyed also on many server machines. You can read more about this here . Most likely it was a Ransom… Read More »

HTTP for IPv6 from client side

IPv6 works in the same way as IPv4 address, however IPv6 addresses must be enclosed in square brackets. It is required to avoid conflict with colon character in protocol specification: http:, https:, ftp:. To test IPv6 installed Apache server on Ubuntu device and enable IPv6. The IPv6 of my Ubuntu device is “2002:ac7:fa01:c71e:250:56ff:fe98:bebd”. First I… Read More »

Favicon for and other WordPress websites

Favicon (favorite icon) is small image that appears with the website title on the browser tab. The icon increases site’s personality and makes it more attractive. When Web browser client downloads favicon files it should be recognized by the web browser as URL icon to be displayed appropriately. Normally browser is informed about favicon through… Read More »

Renci.SshNet default ConnectionInfo values.

Renci.SshNet.dll was already mentioned in current blog. It is client library to connect to SSH servers for example Linux sshd daemon. Similar as other ssh related software Renci.SshNet.dll has list of default Ciphers, Key Exchange Algorithms, Message Authentication Code and other connection settings. These setting are defined in Renci ConnectionInfo class. It is possible to… Read More »

FIPS and Remote Desktop Connection

FIPS or Federal Information Processing Standards was developed by US National Institute of Standards and Technology and used widely not only in United Stated. FIPS defines certain specific encryption methods and make to force application to use FIPS-validated encryption schemes. The first time I met problem with FIPS when Windows computer sends smnp v3 request… Read More »

SSH server on Android phone

SSH is the great thing to troubleshot, transfer files, make some changes or even do development task on remote devices. Smart phone is not an exception and also could be accessible via ssh. Beside ssh client on desktop computer may be more ergonomically friendly than terminal on Android phone with tiny screen and small keyboard.… Read More »