# Section 06: SMTP and DNS enumeration ## SMTP SMTP (Simple mail transfer protocol) > The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. POP3 > In computing, the Post Office Protocol (POP) is an application-layer Internet standard protocol used by e-mail clients to retrieve e-mail from a mail server. POP version 3 (POP3) is the version in common use, and along with IMAP the most common protocols for email retrieval. nmap > Nmap is a network scanner created by Gordon Lyon. Nmap is used to discover hosts and services on a computer network by sending packets and analyzing the responses. Nmap provides a number of features for probing computer networks, including host discovery and service and operating system detection. smtp-enum-users (nmap) > Attempts to enumerate the users on a SMTP server by issuing the VRFY, EXPN or RCPT TO commands. The goal of this script is to discover all the user accounts in the remote system. Dig > Extensive web interface to dig for doing online dns lookup / nameserver query. Nslookup > nslookup is a network administration command-line tool for querying the Domain Name System to obtain the mapping between domain name and IP address, or other DNS records. DNSSEC (DNS security extensions) > The Domain Name System Security Extensions (DNSSEC) is a suite of extension specifications by the Internet Engineering Task Force (IETF) for securing data exchanged in the Domain Name System (DNS) in Internet Protocol (IP) networks. broadcast-dns-service-discovery > Attempts to discover hosts' services using the DNS Service Discovery protocol. It sends a multicast DNS-SD query and collects all the responses. Links * * * * *