> For the complete documentation index, see [llms.txt](https://gabb4r.gitbook.io/oscp-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gabb4r.gitbook.io/oscp-notes/service-enumeration/smtp-enumeration-port-25.md). # SMTP Enumeration (Port 25) ## Quick Intro * Used to send, receive, and relay outgoing emails * Used port 25 * Main attacks are user enumeration and using an open relay to send spam ## NSE ``` nmap 192.168.1.101 --script=smtp* -p 25 nmap --script=smtp-commands,smtp-enum-users,smtp-vuln-cve2010-4344,smtp-vuln-cve2011-1720,smtp-vuln-cve2011-1764 -p 25 $ip ``` ## User Enumeration ``` smtp-user-enum -M VRFY -U /usr/share/wordlists/metasploit/unix_users.txt -t $ip for server in $(cat smtpmachines); do echo "******************" $server "*****************"; smtp-user-enum -M VRFY -U userlist.txt -t $server;done #for multiple servers # For multiple servers ``` ## Connection ``` telnet $ip 25 ``` ### Command to check if a user exists ``` VRFY root ``` ### Command to ask the server if a user belongs to a mailing list ``` EXPN root ``` ## Brute Force ``` hydra -P /usr/share/wordlistsnmap.lst $ip smtp -V ``` ## Send email using netcat --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://gabb4r.gitbook.io/oscp-notes/service-enumeration/smtp-enumeration-port-25.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.