The best thing about CentOS 7 is, it has a super easy firewall built-in. I recommend you not to disable the firewall. To check the active zones: [root@rh7 ~]# firewall-cmd –get-active-zones public interfaces: enp1s0f0 To get available service names: [root@rh7 ~]# firewall-cmd –get-services RH-Satellite-6 amanda-client bacula bacula-client dhcp dhcpv6 dhcpv6-client dns ftp high-availability http https imaps […]

Even though it sounds like a simple problem, a lot of our customers have asked the question why they can’t get back ping responses from their MS Windows servers. The problem is simple, because on most flavors of MS Windows boxes, the firewall has disabled ICMP requests by default. To enable it, go to Start […]

Below I’ll describe a couple of nice methods to generate passwords using Python and Bash. Actually there are a lot of ways you can accomplish this especially with bash, but using the /dev/urandom file seems to be the most clever one. The /dev/urandom device doesn’t only generate read-friendly characters, so it’s best to filter out […]

Earlier we’ve discussed target specification in detail. But it is almost as import to choose your method to scan the target host. Nmap can scan in various algorithms, we should choose wisely considering the network, operating system and firewalls. Even though we usually don’t know what network architecture or operating system the target is affiliated […]

Every now and then, we need to scan ports as system administrators, even if the target machine is owned by us or not. To achieve this, nmap is the well known and reliable tool which is available for almost every platform. But to use nmap, we need to understand the background of it a little. […]

If it appears to be all (***) instead of your mail hostname and if you get, “550 Sorry, your HELO/EHLO greeting must resolve (#5.7.1)” error when sending mail to your mail server from outside, run the following command in your CISCO firewall: no fixup protocol smtp 25 and save with the “wr mem” command