$COMAN2 = ARRAY('NOOP', 'HELO '.HOSTNAME, 'EHLO '.HOSTNAME, 'STARTTLS', 'EHLO '.HOSTNAME, 'AUTH LOGIN', base64_encode($correo), base64_encode($clave), "MAIL FROM: <$scorreo>", "RCPT TO: <$para>");

$COMAN2 = ARRAY('NOOP', 'HELO '.HOSTNAME, 'EHLO '.HOSTNAME, 'STARTTLS', 'EHLO '.HOSTNAME, 'AUTH PLAIN', base64_encode("\0$correo\0$clave"), "MAIL FROM: <$scorreo>", "RCPT TO: <$para>");

openssl s_client -connect HOSTNAME:25 -starttls smtp

depth=2 C=US, O=Internet Security Research Group, CN=ISRG Root X1
verify return:1
depth=1 C=US, O=Let's Encrypt, CN=E5
verify return:1
depth=0 CN=HOSTNAME
verify return:1
---
Certificate chain
 0 s:CN=HOSTNAME
   i:C=US, O=Let's Encrypt, CN=E5
   a:PKEY: id-ecPublicKey, 256 (bit); sigalg: ecdsa-with-SHA384
   v:NotBefore: Jan  7 02:17:31 2025 GMT; NotAfter: Apr  7 02:17:30 2025 GMT
 1 s:C=US, O=Let's Encrypt, CN=E5
   i:C=US, O=Internet Security Research Group, CN=ISRG Root X1
   a:PKEY: id-ecPublicKey, 384 (bit); sigalg: RSA-SHA256
   v:NotBefore: Mar 13 00:00:00 2024 GMT; NotAfter: Mar 12 23:59:59 2027 GMT
---
Server certificate
-----BEGIN CERTIFICATE-----
código
-----END CERTIFICATE-----
subject=CN=HOSTNAME
issuer=C=US, O=Let's Encrypt, CN=E5
---
No client certificate CA names sent
Peer signing digest: SHA256
Peer signature type: ECDSA
Server Temp Key: X25519, 253 bits
---
SSL handshake has read 2665 bytes and written 441 bytes
Verification: OK
---
New, TLSv1.3, Cipher is TLS_AES_256_GCM_SHA384
Server public key is 256 bit
This TLS version forbids renegotiation.
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---
250 CHUNKING
---
Post-Handshake New Session Ticket arrived:
SSL-Session:
    Protocol  : TLSv1.3
    Cipher    : TLS_AES_256_GCM_SHA384
    Session-ID: DC24C1BAC5D62AB810F1D7B10BD33461EB05F07E01E05C0E7FAF58D60EA473DA
    Session-ID-ctx:
    Resumption PSK: 47FD6218DE928B3018F5DF9D39025A5DADCFF01D83B6388E99DECE90A695C80465A1B5432CBD7D779B0A459128BA828D
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 7200 (seconds)
    TLS session ticket:
CODIGO BINARIO
    Start Time: 1736379717
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)
    Extended master secret: no
    Max Early Data: 0
---
read R BLOCK

[root@noel ~]# telnet HOSTNAME 25
Trying IP...
Connected to HOSTNAME.
Escape character is '^]'.
220 HOSTNAME ESMTP Postfix
EHLO HOSTNAME
250-HOSTNAME
250-PIPELINING
250-SIZE 30720000
250-ETRN
250-STARTTLS
250-AUTH PLAIN
250-AUTH=PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING
AUTH LOGIN
535 5.7.8 Error: authentication failed: Invalid authentication mechanism
quit
221 2.0.0 Bye
Connection closed by foreign host.
[root@noel ~]#

[root@noel ~]# telnet HOSTNAME 25
Trying IP...
Connected to HOSTNAME.
Escape character is '^]'.
220 HOSTNAME ESMTP Postfix
EHLO HOSTNAME
250-HOSTNAME
250-PIPELINING
250-SIZE 30720000
250-ETRN
250-STARTTLS
250-AUTH PLAIN
250-AUTH=PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 CHUNKING
AUTH PLAIN
334
=> => => aquí envío el CORREO/USUARIO en formato base 64
535 5.7.8 Error: authentication failed: (reason unavailable)
quit
221 2.0.0 Bye
Connection closed by foreign host.
[root@noel ~]#

535 5.7.8 Error: authentication failed: (reason unavailable)

proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $virtual_mailbox_limit_maps
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
inet_interfaces = all
smtp_tls_security_level = may
disable_vrfy_command = yes
smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = $smtpd_milters
milter_default_action = accept

535 5.7.8 Error: authentication failed: (reason unavailable)

# Global Postfix configuration file. This file lists only a subset
# of all parameters. For the syntax, and for a complete parameter
# list, see the postconf(5) manual page (command: "man 5 postconf").
#
# For common configuration examples, see BASIC_CONFIGURATION_README
# and STANDARD_CONFIGURATION_README. To find these documents, use
# the command "postconf html_directory readme_directory", or go to
# http://www.postfix.org/.
#
# For best results, change no more than 2-3 parameters at a time,
# and test if Postfix still works after every change.



queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
inet_protocols = all
mydestination = localhost, localhost.localdomain
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
debug_peer_level = 2
debugger_command =
PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
ddd $daemon_directory/$process_name $process_id & sleep 5

sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.10.1/samples
readme_directory = /usr/share/doc/postfix-2.10.1/README_FILES


myhostname = HOSTNAME
mynetworks = 127.0.0.0/8
message_size_limit = 30720000
virtual_alias_domains =
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_mailbox_base = /home/vmail
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, check_recipient_access hash:/etc/postfix/script_filter, permit
smtpd_use_tls = yes
smtpd_tls_cert_file = /etc/pki/dovecot/certs/dovecot.pem
smtpd_tls_key_file = /etc/pki/dovecot/private/dovecot.pem
virtual_create_maildirsize = yes
virtual_maildir_extended = yes
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $virtual_mailbox_limit_maps
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
inet_interfaces = all
smtp_tls_security_level = may
disable_vrfy_command = yes
smtpd_milters = inet:127.0.0.1:8891
non_smtpd_milters = $smtpd_milters
milter_default_action = accept

tls_server_sni_maps = hash:/etc/postfix/vmail_ssl.map
smtpd_data_restrictions = check_policy_service unix:/var/log/policyServerSocket
smtpd_policy_service_default_action = DUNNO
smtpd_data_restrictions = check_policy_service unix:/var/log/policyServerSocket
smtpd_policy_service_default_action = DUNNO
smtpd_data_restrictions = check_policy_service unix:/var/log/policyServerSocket
smtpd_policy_service_default_action = DUNNO

[root@pepsi ~]# postconf mail_version
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_client_restrictions
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_helo_restrictions
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_sender_restrictions
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_client_restrictions
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_helo_restrictions
postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_sender_restrictions
postconf: warning: /etc/postfix/main.cf: undefined parameter: virtual_mailbox_limit_maps
mail_version = 3.9.1
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_create_maildirsize=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_maildir_extended=yes
postconf: warning: /etc/postfix/main.cf: support for parameter "smtpd_use_tls" will be removed; instead, specify "smtpd_tls_security_level"
[root@pepsi ~]#

21:03:03.756744 conectado a HOSTNAME en el puerto 25
21:03:06.855631 220 HOSTNAME ESMTP Postfix
21:03:06.855657 NOOP
21:03:06.855809 250 2.0.0 Ok
21:03:06.855824 HELO HOSTNAME
21:03:06.855940 250 HOSTNAME
21:03:06.855950 EHLO HOSTNAME
21:03:06.856074 250-dns.HOSTNAME
21:03:06.856081 250-PIPELINING
21:03:06.856085 250-SIZE 30720000
21:03:06.856088 250-ETRN
21:03:06.856091 250-STARTTLS
21:03:06.856094 250-AUTH PLAIN
21:03:06.856097 250-AUTH=PLAIN
21:03:06.856100 250-ENHANCEDSTATUSCODES
21:03:06.856103 250-8BITMIME
21:03:06.856106 250-DSN
21:03:06.856109 250 CHUNKING
21:03:06.856113 STARTTLS
21:03:06.856210 220 2.0.0 Ready to start TLS
21:03:06.912122 EHLO HOSTNAME
21:03:06.912480 250-HOSTNAME
21:03:06.912500 250-PIPELINING
21:03:06.912505 250-SIZE 30720000
21:03:06.912509 250-ETRN
21:03:06.912512 250-AUTH PLAIN
21:03:06.912515 250-AUTH=PLAIN
21:03:06.912518 250-ENHANCEDSTATUSCODES
21:03:06.912521 250-8BITMIME
21:03:06.912524 250-DSN
21:03:06.912527 250 CHUNKING
21:03:06.912532 AUTH PLAIN
21:03:06.913105 334
21:03:06.913125 cmdAbWVqb3JhbW9zLmNvbQ==
21:03:08.415445 535 5.7.8 Error: authentication failed: (reason unavailable)
21:03:08.415472 QUIT
21:03:08.415867 221 2.0.0 Bye

sudo touch /root/pruebita.txt

[root@localhost ~]# ls -l /root
total 16
-rw-r--r--. 1 root root 7512 Oct 29  2020 anaconda-ks.cfg
-rw-r--r--  1 root root  392 Apr 18 13:58 pruebita.txt
-rw-r--r--. 1 root root  134 Oct 29  2020 README
[root@localhost ~]#

[u2023@localhost ~]$ ls -l /root
ls: cannot open directory /root: Permission denied
[u2023@localhost ~]$


[u2023@localhost ~]$ echo 'elhacker.net' > /root/pruebita.txt
-bash: /root/pruebita.txt: Permission denied
[u2023@localhost ~]$


[u2023@localhost ~]$ sudo echo 'elhacker.net' > /root/pruebita.txt
-bash: /root/pruebita.txt: Permission denied
[u2023@localhost ~]$

u2023 ALL=(ALL) NOPASSWD:ALL

-bash: /root/pruebita.txt: Permission denied