NMAP UDP DNS scan unexpected packets sending

I got the other day an automated mail alert from some ID/IPS equipment that ‘ a NULL DNS scan was detected and blocked from your IP’. NULL DNS scan? I wasn’t sending any such packets, not to mention I have no idea what they mean by that. After some …



Last measure for the desperate case of a lost access to the Check Point firewall

It may happen to anyone – mistaken security rule “Any Any Drop”, or using dynamic object for URL block. The end result – after the policy install you have no administrative access to the firewall with SmartDashboard/ssh/https. For this case Check Point came with fw unloadlocal console/SSH expert level …



How many times can we change IP address of the Check Point license?

TLDR: 6 times. Today most licenses are of a central type so we rarely need to change their IP address as IP address of the Management server does not change that often. Still, if this happens then there is an option to change IP address or re-license the existing license …



NMAP run stages flow diagram

NMAP scanner has become over the years so friendly that it is not apparent what is going on when it runs. Below is a typicsl NMAP workflow: Follow me on https://www.linkedin.com/in/yurislobodyanyuk/ not to miss what I publish on Linkedin, Github, blog, and more.



Hex editor of binary files on Linux

Reading this thread on Stackoverflow http://stackoverflow.com/questions/5498197/need-a-good-hex-editor-for-linux I wondered how come with so many hex editors in Linux there is not really the best one. In Windows it is easier - the expensive WinHex or the affordable Hiew. Anyway, as to the Linux I always use Vim …



Ever wondered how much does ip addresses allocation cost to your service provier ?

Ever wondered how much does IP addresses allocation really cost to your provider? Well, that is easy. If we talk about the RIPE IP address space (majority today) then they have published their fees for PI (Provider Independent) allocations for LIRs (Local Internet Registry) which is by coincidence your ISP …



Public DNS servers open to any on the Internet

Following the good will by Google many other providers made their DNS servers available to us without any limitations as recursive resolvers. As they do not announce it widely enough you may not have heard abouth them, here is the list of these DNS servers: OpenDNS/Cisco Umbrella: 208.67 …



Linux ip route command reference by example

ip address - Manage IP address(es) on interfaces ip route - Manage routing table ip link - Link Management Interface Grouping. ip neighbor - Managing ARP table Tunnel interfaces GRE NOTE: All the commands below take effect immediately after you hit Enter, and do NOT survive reboot. ip address - Manage IP address(es …



Free public NTP servers from Google

It has passed somewhat unnoticed but Google have made available to us their free, accessible to all NTP servers. I have been using their DNS servers for years without any issues so will trust their NTP ones as well. So far works just fine. For a single server we can …



Disconnect VPN or Mobile Access or SNX user from Check Point firewall

You may need occasionally to disconnect some or all connected users from the firewall forcibly. There are few ways I can think about to do so, for example installing Security Policy clears the cached authentication of the remote users, and while it does not disconnect them it will force a …