May 19 2015

IPTables Auto-Expiring Rules on Linux.

NetFilter IPTables Project Auto-Expiring Rules could be very interesting (for example) to ban IPs for a certain amount of time, and then have then automatically un-banned (by removing Filtering Rule).

IPTables do not provide an integrated solution for that, but a simple combination with the ‘at’ command can do the magic.
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Apr 3 2015

Anacron run-parts: /etc/cron.daily/amavisd-new exited with return code 1.

Messages like the ones in the article list, originated from a cron job, could be generated on debian systems:

/etc/cron.daily/amavisd-new:
Please run this cronjob as user amavis
run-parts: /etc/cron.daily/amavisd-new exited with return code 1

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Mar 20 2015

Mikrotik IPSec VPNs with multiple destination Networks/Policies and SA(s) management.

While configuring Multiple Networks VPNs (Multiple policy and destination SubNets reached via the same remote IPSec VPN Peer) between Mikrotik and other Firewalls, traffic would randomly stop for certain destinations.

Packet forwarding and encryption only works for one destination (the first matched IPSec Policy) and any other destination (and only the first matched one) will be reachable by performing a ‘SA Flush’.

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Dec 11 2014

Extracting a Single Database From a mysqldump File containing –all-databases Dump.

Imagine to have a full MySQL DB Dump (containing a lot of Single Database Dumps) and imagine also to need the extraction or restoration of a single one. This is a quite common task that can be accomplished using some shell commands.
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Oct 3 2014

Protect Servers Against Shellshock Bash Vulnerability.

On September 24, 2014, a GNU Bash vulnerability (Shellshock or “Bash Bug”), was discovered and published.
The vulnerability allows remote attackers to execute arbitrary code given specific conditions, by injecting strings of code following environment variable assignments.
Because of Bash’s large utilization (Ex: Linux, BSD, OsX), many computers are vulnerable to Shellshock Bash Bug.
All unpatched Bash versions between 1.14 through 4.3 seems to be compromised.
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