Posts related to computer networks

How to split DNS DKIM records

DNS TXT records do have a limitation. Strings must not be longer than 255 Bytes. This limitation can hurt you with SPF records or DKIM records. In this case you…

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Hide your version of BIND

To hide your version of bind, enter the following value to your named.conf version "[NONE]"; in the option section: options { directory "/var/lib/bind"; version "[NONE]"; }; Check the value with…

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Subnet Masks

A subnetwork, or subnet, is a logically visible, distinctly addressed part of a single Internet Protocol network. The process of subnetting is the division of a computer network into groups of computers that have a common,…

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pcap filter

tcpdump and ngrep are both based on libpcap. Therefore both use the same filter expressions. Here is the manual page of the ⇒pcap filter expression. These filter expressions are also…

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