Postfix on bare CentOS install


Starting from scratch with a new CentOS 7 Linode, I found that iptables is set by default to block (although not reject) packets to the IMAP and POP3 services.

Rackspace has a good primer on setting up Dovecot that includes these instructions, but here's the short answer:

sudo iptables -I INPUT 2 -p tcp --dport 587 -j ACCEPT sudo iptables -I INPUT 3 -p tcp --dport 110 -j ACCEPT sudo iptables -I INPUT 4 -p tcp --dport 143 -j ACCEPT sudo iptables -I INPUT 5 -p tcp --dport 993 -j ACCEPT sudo iptables -I INPUT 6 -p tcp --dport 995 -j ACCEPT sudo /etc/init.d/iptables save sudo /etc/init.d/iptables restart

That adds a rule to accept the IMAP and POP ports, both the regular and SSL versions. Then we save the chain table and restart iptables. Now you should be able to get in: $ telnet imap Trying Connected to Escape character is '^]'. * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS LOGINDISABLED] Dovecot ready.

Updating Subversion in Centos 5.5


Interacting with modern Subversion repositories requires a modern copy. Centos 5.5, and other previous versions however, have rather old copies. My server reported (typed text underlined) --

# <span style="text-decoration: underline;">rpm -qa|grep subversion</span>

The first step is to disable the yum-priorities plugin, if you are using it. If it exists, edit the file /etc/yum/pluginconf.d/priorities.conf and set enabled=0 -- you may want to change it back after you are done here.

Now let's see which subversion we have installed.

<code>  $ rpm -qa|grep subversion

Ah, right. Version 1.4.2 ... We want at least 1.5.

Install the rpmforge repository, following the CentOS instructions. There are the commands I used, you will want to verify the latest version.

# <span style="text-decoration: underline;">wget</span>
# <span style="text-decoration: underline;">rpm --import</span>
# <span style="text-decoration: underline;">rpm -K rpmforge-release-0.5.2-2.el5.rf.*.rpm</span>
# <span style="text-decoration: underline;">rpm -i rpmforge-release-0.5.2-2.el5.rf.*.rpm</span>

RPMs that overwrite base CentOS modules have been removed from the main rpmforge repository, and put into the rpmforge-extras repository. Unfortunately that is disabled by default, and it is less than obvious how to enable it. The setting is in /etc/yum.repos.d/rpmforge.repo ... Look for this stanza and change the enabled line:

name = RHEL $releasever - - extras
baseurl =$basearch/extras
mirrorlist =
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge-extras
<strong>enabled = 1</strong>
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-rpmforge-dag
gpgcheck = 1

After this, you can just do a regular yum update or you can manually do just the one:

<pre style="padding-left: 30px;"><code>$ yum --enablerepo=rpmforge check-update subversion
subversion   </code>subversion-1.6.15-0.1.el5.rfx<code>         rpmforge

XWindows (Linux) Mouse control with keypad


Handy when you need it and frustrating when you forget how you accidentally turned it on: That's XWindows' keypad mouse mode.

It is actived by pressing "Num Lock" while holding down the Shift key. Hit Shift + NumLock again to toggle out of the mode.

The numbers around the edge (7,8,9,6,3,2,1,4) move the cursor up, down, left, right, and diagonally. 5 and Enter become left-click; 0 becomes right-click.

Finding the UUID of a drive to mount on Linux


$ <strong>tune2fs -l /dev/sdc2</strong>
tune2fs 1.35 (28-Feb-2004)
Filesystem volume name: root
Last mounted on:
Filesystem UUID: 7d99ac7d-9fc5-42ea-8f47-f2fb92b6b8de


and then in /etc/fstab you can specify a mount-point, for example:

UUID=7d99ac7d-9fc5-42ea-8f47-f2fb92b6b8de /home           ext4    defaults        0       2

Suspend fails on Dell Inspiron 8600


Applies to: Ubuntu Linux 9.10, 10.04

Reason: Laptop suspends but does not awaken properly. Screen is black, with or without cursor, does not respond to keyboard. Issue is that display backlight is not restarted.

Resolution: Per comments and instructions in the Lanuchpad Bugs site, in file /usr/share/hal/fdi/information/10freedesktop/20-video-quirk-pm-dell.fdi

Find and change by adding the bold text:

<!-- Dell Inspiron -->
 <match key="system.hardware.product" prefix="Inspiron">
<strong> <match key="system.hardware.product" contains_outof="1501">
</strong> <match key="system.hardware.product" contains_outof="1501;8600">