Linux   Linux – Exim: Authenticated and TLS mail through smarthost



Exim is a very flexible and common MTA (mail transfer agent) in Unix systems.
This posts shows the way to configure Exim as client to send authenticated and encrypted (TLS) emails through a smarthost.

Lets suppose the smarthost email server is listening on port 587 for secure outgoing SMTP…

Configure exim to use the smarthost

To configure exim In … Read more

Linux   Linux – TCP listener daemon with tcpserver



To configure passive checks in Nagios/icinga I use a tcp listener daemon that launches a script (See Nagios – Using passive checks without agent)
Tried to use inetd superserver daemon, but in the last versions, i have not been able to make it work correctly (See last update in my post: Linux – cannot found / missing inetd.conf)Read more

Linux   Linux – cannot found / missing inetd.conf



Trying to configure a new inetd service needed for my Icinga (see Linux – Create custom inetd service), but i have not been able to find the inetd.conf file.
It seems inetd is not installed by default in the last Debian versions (mine is 9 – stretch).

Luckily, it is packetized in the inetutils-inetd

# apt-get install inetutils-inetd
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F5 BIG-IP icon   F5 BIGIP – Send logs to custom syslog file



For debugging purposes (or to simply to organize logs as you prefer) it would be interesting to send certain syslog messages to a custom file instead of the default ones like /var/log/ltm or /var/log/apm

Desired goal

This example shows the way to send syslog messages starting with the string #DEBUG# to the file /var/log/customlog

(You can replace both string and Read more

Linux   Linux – Create multiboot CD combining multiple ISO images



This post shows the steps to create a multiboot cd with multiple Linux distributions or tools.

For example, I created a recovery / disaster case cd with the following tools:
Clonezilla (to clone/recover disks and partitions)
Gparted (partition editior with GUI)
Trinity Rescue Kit (linux distribution for recovery and repair operations on Windows machines)

The Multicd Read more

F5 BIG-IP icon   F5 BIGIP – Bug when using datagroups in LTM policies



Datagroups can be used in LTM policies to, for example, filter connections based on the client IP address (at least in my BIG-IP v13.0.0)

This is possible by adding a condition like this:
F5 BIGIP - Bug when using datagroups in LTM policies 1

“TCP” – “address” – “matches” – “in datagroup” <DATAGROUP> – at “request” time
(apply traffic on “remote” side of “external” interface)

Problem

This works correctly when the … Read more

Raspberry icon   Rasbperry – NO-IP configuration to be ran at boot time



If you need to update automatically a DNS entry with your public IP address (for example, to allow remote access to your home Raspberry or Linux), you can use the no-ip provider and its Linux or Raspberry client.

This posts shows the way to install the client and how to configure it to be started at boot time.

Register at

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Security   Security – Convert PFX to PEM using Windows or Linux



For certain application, a job partner asked me to send him certain certificate with private key in PEM format. Normally I’m using PFX format, but with a little help of the openssl toolkit converting PFX to PEM is quite easy.

Windows

openssl for windows can be downloaded here: http://gnuwin32.sourceforge.net/packages/openssl.htm
After extracting the contents, inside the bin subfolder the openssl … Read more

F5 BIG-IP icon   F5 BIGIP – Modify URI path using local traffic policy



Im using my F5 BIGIP (v13) as reverse proxy to publish some websites by using local traffic policies. But i need to perform a URL rewriting. To be specific, i need to strip a string from the URI path.

It could be done using an IRule:

when HTTP_REQUEST{
if { [string tolower [HTTP::uri] ] starts_with "/path1" } {
  HTTP::uri [string 
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F5 BIG-IP icon   F5 BIG-IP – Rollback tmsh commands



Today a very short and simple post to learn how to rollback configurations performed via tmsh.
After executing some commands, if finally we need to undo those changes we can get it, at least, by the following ways:

    • In case of HA environment, the standby node configuration can be sync so that we set the active (changed) node to
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