Skip to main content

Test STARTTLS SMTP Connection

Run the following command to connect

openssl s_client -connect {server}:{port} -starttls smtp

Then find out what authentication is supported. It should now show "AUTH LOGIN" now that you have an encrypted connection:

ehlo {domain.com}

If you see "AUTH LOGIN" in the list then do the following:

Common firewall-cmd Examples

List all zones:

 firewall-cmd --list-all-zones

List all active zones:

firewall-cmd --get-active-zone

To add a host or network to allow all connections from:

firewall-cmd --permanent --zone=trusted --add-source=10.10.10.10

Add a service to be allowed from anywhere:

firewall-cmd --permanent --add-service=smtp

When you run firewall-cmd with the "--permanent" it will not be active until the dameon is reloaded. Do the following to make them active:

firewall-cmd --reload

Checking for Bad Blocks on a Hard Drive in Linux

In Fedora, the badblocks program is part of the e2fsprogs program. You probably already have that installed. But in case you don't do the following:

yum install e2fsprogs

To just see the bad blocks the following to do a non-destructive read/write test:

badblocks -nvs /dev/sda

To generate generate a list of the bad blocks do the following:

badblocks -nv /dev/sda > badblocks.txt

Now you can mark the bad blocks found with the following:

Sharing Desktop in Fedora 18

NOTE: This is an update from my previous post on sharing the desktop or running a VNC Server. This method works great in Fedora 18.

First install the vino package:

yum install vino

Then click on Activities in the top left corner of the screen.

Next type in "vino" and click on "Desktop Sharing" under Applications or under Settings.

Next click "Allow other users to view your desktop". Make sure "Allow other users to control my desktop" is also check.

Fix Adwaita Theme in Fedora 18

In Fedora 18 the Adwaita GTK+ theme has dropdowns messed up in some programs. The text on the drop downs is light grey on white and it's hard to read.

To fix this install the Gnome Tweak tool and a different GTK+ theme:

yum install greybird-gtk2-theme greybird-gtk3-theme gnome-tweak-tool

Then open Tweak Tool. Under "Gtk+ Theme" select "Greybird".

Saving iptables in Fedora 15 or Greater

In older versions of Fedora (14 or less) you could save your current iptables with the following command:

service iptables save

This would take the tables you currently have in places and save them to the following file:

/etc/sysconfig/iptables

So you could added/delete/change any tables you want then save them so they would be correctly re-applied on the next boot.