IT Blog - Vyacheslav Gapon - personal blog, manuals, articles, notes, development

iRedMail: Attachment Blocking with Amavis

It was necessary to block certain attachment formats, as they were often used to send malicious data.

Script for polling ONU RX Power from BDCOM OLT

When connecting new subscribers, operators needed to check the optical level of the new ONU. ONUs didn’t appear immediately in the billing system. So, I first enabled a web interface on the OLT with limited access via ACL and a separate account with read permissions. However, the web interface page often opened with significant delays. So, I wrote a PHP script that displays the optical levels of all ONUs in a couple of seconds.

FTP backup script

Here’s an example of a simple script for synchronizing directory files from a remote server via FTP, for example with backup archives.

ProFTPd. IP Access Restriction

Access by IP address or subnet in ProFTPd is very easily restricted.

Medoc. Database Error Fixes

One day, after a Medoc update, an error occurred while filling in counterparty data from the directory. I was asked to investigate. It turned out to be a bug. Medoc support sent me a patch, and a couple of days later they released an update for other users. But while I was searching for the cause, I discovered that there were errors in the database.

How to set up mTLS

Let’s say you need to configure mTLS for communication between two servers, for example, for requests from a website to an API server.

How to remove characters from the end of lines in Notepad++

Once, when generating commands for configuring the OLT, I needed to take part of the configuration of a working device and remove 2 characters from the end of each line.

Meest Cargo delivers goods from China to sole proprietors

I placed another order with one of my familiar suppliers in China, with delivery to a sole proprietor and payment of all taxes.

Huawei HS8346X6-C Firmware Update

I once needed to open remote access via the WAN port to a Huawei HS8346X6-C ONU. I periodically had to open the web interface and forward ports to various devices. However, it turned out that this ONU didn’t have Remote Management in its settings. So I contacted the supplier in China for new firmware.

Configuring Cloudflare’s CF-Connecting-IP Header

Since when Cloudflare proxy is enabled, requests to the web server will come from Cloudflare servers, and not directly from users, you need to configure the CF-Connecting-IP header, which transmits the user’s real IP address. After configuration, it will be displayed as before in logs and requests.