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Remote-reboot Polycom phones using SIP NOTIFY
by lunarg on November 4th 2011, at 14:51
You can remote-reboot your Polycom phones from the Asterisk CLI by sending a SIP NOTIFY command. This command instructs the phone to recheck its configuration, and therefore, will reboot when certain parameters have been set in your phone configuration provisioning.

Make sure the following directive is set in your provisioning config:

<specialEvent voIpProt.SIP.specialEvent.checkSync.alwaysReboot="1" />

You find this in sip.cfg, or you can set it in your own configuration (mine's called aaps-settings.cfg, but that's just an arbitrary name).

Notice

When setting this variab  ...
 
Postfix: block SMTP access by IP
by lunarg on September 28th 2011, at 12:23
If you wish to restrict SMTP access via IP addresses or a network range, one way to do it would be via Postfix configuration. You can set up restrictions using a Postfix hash-table or via a cidr file. You can choose one or both methods to perform the restrictions. The end-result will be the same.

Create a text file with the addresses you would like to reject. You can choose whatever file name you wish. E.g.: /etc/postfix/smtp_client_access

Its content should be something like:

192.168.0.1 REJECT Stop mailing us192.168.0.2 REJECT Stop mailing us192.168.1 REJECT Stop mailing us

Next, postmap  ...
 
Automated backup of PostgreSQL in linux
by lunarg on June 5th 2011, at 13:17

To have scripted automated backup of PostgreSQL databases on a linux platform, you can create a script like so:

#!/bin/bash
PGPASSWORD="your-password" /usr/bin/pg_dump -U user database > sql-file.sql

Replace user and your-password with your username and password; replace database with the database you want to backup. The output of the dump goes to stdout and can be piped to a plain text file or compressed to something else.

 
Debian: turn off incremental (pdiff) package updates
by lunarg on October 20th 2010, at 11:57
Debian has introduced incremental updating of package lists. While in theory, this is a great feature, it is not always practical.

Incremental updates enable to download less data by fetching only the differences between the previous versions of the list. This results in significant savings concerning the amount of downloaded data.
The unfortunate downside is that a whole lot more fetches need to be done as each incremental update requires a server request. This becomes apparent when you don't often download package list updates, and there are suddenly a whole number of files waiting to be do  ...
 
Batch processing with The GIMP
by lunarg on August 26th 2010, at 12:53
While batch processing was already possible using the rather complex Script-Fu, there's now a plug-in for GIMP allowing simple batch processing through a dialog.

DBP David's Batch Processor allows for automatic operations on a collection of image files. Operations such as colour correcting, resizing, cropping, sharpening, and even renaming can be performed with ease, saving them to a different location in a different image format. All operations (except loading and saving) are optional so you can use this for simple image format conversion as well.

DBP can be found here: http://me  ...
 
nano syntax highlight for Shorewall config files
by lunarg on August 24th 2010, at 16:31

This package provides files to enable syntax highlighting in nano when editing shorewall configuration files, making it easier to maintain these kinds of files.

 
Determine shell script's own location
by lunarg on August 23rd 2010, at 16:47

For a shell script to determine its own location, you can use this code snippet. It takes relative and absolute paths into account.

#!/bin/bash
if [[ $0 == '/'* ]]; then
	MYLOCATION="`dirname $0`"
else
	MYLOCATION="`pwd`"/"`dirname $0`"
fi
echo "My location is: $MYLOCATION"
 
Regenerating SSH host keys
by lunarg on August 19th 2010, at 16:19

If for some reason you lost your SSH server keys, sshd will fail to start with error:

Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_dsa_key

You can recreate your host keys with these commands:

ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key
ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key

After recreating the keys, you will probably have to let your clients know as with the change of keys, they'll probably get warnings about it (Linux SSH will not even connect until you kick out the old keys).

 
IPSEC on multi-WAN linux firewall
by lunarg on June 23rd 2010, at 17:14
Working on implementing Multi-WAN at our office (more about that later), in which we use a rather special routing setup, we got this error message on our IPSEC tunnels:

Quote

ipsec_setup: Starting Openswan IPsec U2.4.12/K2.6.26-2-amd64...
ipsec_setup: no default route, %defaultroute cannot cope!!!

While the reason was obvious to me (there's indeed no default route in the main routing table, this is by design), fixing the problem was not.
I tried adding options like leftnexthop=ip-address but it did not really matter; the error persisted.

After searching around Google, I cam  ...
 
Fiddling with Shorewall
by lunarg on June 3rd 2010, at 20:03
Linux has always been a great player in internetworking, thanks to a very advanced networking stack. In addition, the filtering capabilities provided by Netfilter are only surpassed by a very select group of devices. It doesn't come as a surprise there are a lot of firewalls and internet gateways out there that are running this powerful combo.
Detailing the features of linux as a firewall/internet gateway would take up an entire article so I'm not going to elaborate on it. It suffices to say that whatever you can think up of setting up, the linux + netfilter combo can probably do it. Worst cas  ...
 
Maximum message size in Postfix
by lunarg on April 14th 2010, at 20:22

Like any other MTA, Postfix has a maximum message size that it allows to pass through. By default, when not defined, it is set to 10 MB.
To change it, add/change the following in main.cf:

message_size_limit = 15728640

This sets the limit to 15 MB. To make it unlimited, set it to 0.

 
php_flag vs. php_value
by lunarg on April 1st 2010, at 15:14
Had an issue where I was not able to change the post_max_size and upload_max_filesize through the Apache2 configuration.
After googling around, I finally found what was wrong: apparently, aside of php_flag, there's also a php_value flag to set configuration variables. The difference?

Use php_flag only when setting boolean values like 0 | 1, off | on.Use php_value to actually set values other than boolean (like the filesizes of post_max_size and upload_max_filesize).

Thus, a working example looks like:

<Directory /var/www/> <IfModule mod_php5.c> php_flag register_globals o  ...
 
Incoming PPTP VPN passthrough on OpenWRT
by lunarg on February 1st 2010, at 16:46
To set up a Windows PPTP VPN server behind your OpenWRT enabled router, you need to forward the necessary ports and protocols, and install the proper modules.

Finding information about how to do this was a lengthy process. I never actually found the necessary info (although I noticed there are quite a few people which are rather clueless about networking; makes me wonder why they're bothering with OpenWRT in the first place, it's not the easiest firmware out there).
But I've managed to compile the bits and pieces of various sources into a coherent mass. It's not a guide in the literal sense,   ...
 
SpamAssassin and 2010
by lunarg on January 6th 2010, at 10:18
Versions 3.2 of SpamAssassin have (until very recently) a bug in their rules which would mark mails dated 2010 (this year) as being spam.

The reason for this is that a rule exists which would add an additional score of 3.2 to mails with a date set to 2010, because when the rule was created, the date would be in the very far future. Of course, this is no longer the case.

The bug was already discovered in 2008, and resolved in the SpamAssassin repositories, but was not backported to 3.2 until 2010-01-01, when the issue was discovered by Mike Cardwell, a developer in the UK.

Users with this pr  ...
 
Keep-alive issues when proxying IIS with Apache2
by lunarg on September 8th 2009, at 18:26
We had a bit of trouble with an Apache2 server, configured as a front-end proxy for a IIS running various different sites. The idea for this has grown because of the fact that our client had only one public IP address at the time, but had to run multiple sites. Rather than running the sites in IIS on different ports, we setup the Apache2 to proxy requests to the IIS back-end, so the sites were accessible by means of sub-urls.
E.g.:

http://myserver/mysubdomain1/ -> http://internal-ip:my-port/

For this, we used mod_proxy, and the ProxyPass and ProxyPassReverse.

Lately, our client complained o  ...
 
Installing r8168 driver in 2.6.24
by lunarg on May 1st 2008, at 14:22
Currently, the Realtek R8168 driver does not work in a 2.6.24 kernel because of changes in the kernel structures. I found a patch on the Ubuntu Forums which adjusts the driver source so it can compile for a 2.6.24 kernel. The patch was written for 8.005.00, but I verified it working for 8.006.00 (latest version at time of writing). The patch is attached.

Download driver here.Got the patch from here, but for your convenience, I've attached it to this article too.Note that these instructions are also found on the page at Ubuntu Forums

After unpacking the driver, copy the patch in ./r8168-8.006  ...
 
Virtualbox: set up port forwarding when using NAT
by lunarg on April 17th 2008, at 12:56
If you're using NAT for networking with your VMs, you need to use port forwarding if you want to access a VM from the outside network. This is a quick and dirty howto on how to do this in linux.

Fire up a terminal, and enter these commands:

VBoxManage setextradata nvm3 "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/HostPort" 28080VBoxManage setextradata nvm3 "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/GuestPort" 28080VBoxManage setextradata nvm3 "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/Protocol" TCP

In the sample above, I'm forwarding port 2  ...
 
[Gentoo] No module named collections error with portage
by lunarg on March 26th 2008, at 13:17
Had an issue on my PC at work with a corrupt reiser4 filesystem (still no clue as to why). I managed to repair the FS using RiP-Linux, but not without some data loss. After reviewing lost+found, I found most files related to some HTML cache of Konqueror, but fsck.reiser4 complained about a file that could not be recovered.
After awhile, I tried running emerge to install some new package, and there it was: a broken portage...

The error I got:

!!! Failed to complete portage imports. There are internal modules for !!! portage and failure here indicates that you have a problem with your&nbs  ...
 
Reiser4 sources still available...
by lunarg on March 6th 2008, at 10:36

Namesys, the commercial developer of the Reiser4 filesystem, still has its website down. However, the source code and development is still going on, and can be retrieved at:

http://chichkin_i.zelnet.ru/namesys/

A good thing, because it would be a shame to lose such a good filesystem...

 
The LiveCD List
by lunarg on March 5th 2008, at 09:29

A collegue sent me this link. It's a list of most (if not, all) LiveCDs currently available, with links to their respective websites. Additionally, they have been classified according to functionality.

http://www.livecdlist.com/

 
 
showing posts tagged with 'linux'
 
 
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