Category Archives: sysadmin

Linux, sysadmin

Postfix TLS Support

What Postfix TLS support does for youTransport Layer Security (TLS, formerly called SSL) provides certificate-based authentication and encrypted sessions. An encrypted session protects the information that is transmitted with SMTP mail or with SASL authentication.NOTE: By turning on TLS support in Postfix, you not only get the ability to encrypt mail and to authenticate remote SMTP clients or servers. You also turn on hundreds of thousands of lines of OpenSSL library code. Assuming that OpenSSL is written as carefully as Wietse’s own code, every 1000 lines introduce one additional bug into Postfix.Topics covered in this document:How Postfix TLS support worksSMTP Server specific settingsSMTP Client specific settingsTLS manager specific settingsBuilding Postfix with TLS supportReporting problemsCreditsAnd last but not least, for the impatient:Getting started, quick and dirty

Source: Postfix TLS Support

Linux, sysadmin

16.04 – How to eliminate EDID checksum errors? – Ask Ubuntu

Set the video settings for kernel boot options via grub:

sudo nano /etc/default/grub

Add this line, or change it to this, or add this to the current line (if you know what you’re doing). You can adjust the mode_options, the most import magic is nomodeset and noedid, minimally you can try just adding the noedid:

GRUB_CMDLINE_LINUX_DEFAULT="nomodeset video=uvesafb:mode_options=1024x768-16@60,mtrr=0,scroll=ywrap,noedid"

This turns off KMS mode switching in the kernel; Use the uvesafb frame buffer; Set it to a resolution of 1024×768, with a depth of 16 at 60 Hz sync rate (other options can be 1920x1080-16, or 1600x1200-32@50, depends on your hardware) ; disable the memory type range registers (mtrr) for the framebuffer; enable display panning in a wrap-around mode, using VESA protected mode; do not probe the display to check for edid data. When you switch over to it or connect it to a monitor, then it should be set to that mode (already).

sudo update-grub

To make the grub settings get written to your /boot. Reboot and check it’s working, with noedid you won’t necessarily get a working display if you plug a different monitor in, possibly it could break (eg if the frequency is set higher than the display can handle; though I think modern displays avoid this).

Source: 16.04 – How to eliminate EDID checksum errors? – Ask Ubuntu