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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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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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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Sep 12 2014

PGP Key Security generating and using SubKeys.

Loosing the private key it’s bad, but if someone steals the private key, it’s a disaster.
Thieves can not only decrypt personal data, they can also impersonate the owner by signing messages with his private key.
Yes, it is possible to revoke the stolen key, but that would mean probably loose years of signatures and basically creating a massive inconvenience to redistribute a new public key to the world. SubKeys can help to prevent this disaster.

Having separate SubKeys makes key management easier and protects you in certain occasions, for example it is possible to create a new SubKey when a previous one gets stolen, without losing previous signatures.
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Sep 11 2014

SSH Authentication with PGP Keys.

PGP keys and SSH keys can share the same RSA algorithm and for this reason, with some little tuning it is possible to use a PGP SubKey to authenticate users into SSH Servers.
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