Category Archives: Security

Linux : How to change the OpenVPN lockout time policy

By default, OpenVPN has 15 minutes timeout lockout policy for consecutive unsuccessful authentication attempt (whatever you are using Local, PAM or LDAP authentication). If you want to change it to shorter or longer time period, follow these easy steps below : 1. Push the new timeout value to the configuration using this command (this example… Read More »

JunOS : Port forwarding on Juniper SRX

A friend of mine who was used to the legacy and EOL SSG/ScreenOS platform and he just jumped into the new world of SRX/JunOS gave me the motivation to write this article. As the syntax is quite different between the two platform, it may be harder to get at first and the following example should… Read More »

Windows : Nmap error dnet: Failed to open device eth0

Experiencing the following issue with Nmap on Windows? $ nmap -P0 -sS -T5 0.0.0.0 Starting Nmap 7.70 ( https://nmap.org ) at 2019-06-04 03:14 ric dnet: Failed to open device eth0 QUITTING! It appears that some version of Npcap (or WinPcap) is causing issues. Updating Npcap to version 0.995 solve this issue. If you are running… Read More »

Web : SSL error NET::ERR_CERT_SYMANTEC_LEGACY

Since April 2018, I have noticed the following SSL error with Google Chrome and Safari’s latest versions : NET::ERR_CERT_SYMANTEC_LEGACY All Symantec SSL/TLS certificates issued prior June 1st 2016 will output this warning from now on since the latest updates. Web user, nothing is wrong on your side, the site owner must re-issue his certificate, even… Read More »

ScreenOS : SSL error accessing the WebUI

If you are using the WebUI to manage your Juniper SSG / ScreenOS device, you probably encountered the following error accessing the page lately : ERR_SSL_VERSION_OR_CIPHER_MISMATCH If you use a browser that allow SSLv3, you will be able to access the device. However as we all know the weakness of this protocol, it isn’t ideal… Read More »

ScreenOS : ERR_SSL_VERSION_OR_CIPHER_MISMATCH accessing WebUI

You probably encountered the following error if you are a fan of using the Juniper SSG/ScreenOS WebUI using a “modern” browser : ERR_SSL_VERSION_OR_CIPHER_MISMATCH Well, since the latest clustered SSL exploits, the vast majority of browsers decided to disable some protocols and ciphers for everyone’s safety. To work around this issue, you may use the following… Read More »

Linux : Port forwarding with IPtables

Need to forward a custom port to an existing port on your Linux box? Simply use the following command as root :

Example : Assuming you want to forward port 1025 to port 587 :

The command above won’t survive to reboot, see the configuration below to enter in the IPTables script :… Read More »