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Module 5

Module 5. Securing SCO office Server. CHANGE THE. ADMIN PASSWORD!. Securing SCO office Server. SMTP Server. 25. SCO office Server. Firewall. Internet. 80/443. WebClient. 21 * 25 80/443*110/995 143/993 389/636. Outlook. * Not used by Outlook Express.

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Module 5

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  1. Module 5 • Securing SCOoffice Server

  2. CHANGE THE ADMIN PASSWORD! Securing SCOoffice Server

  3. SMTPServer 25 SCOofficeServer Firewall Internet 80/443 WebClient 21*2580/443*110/995143/993389/636 Outlook * Not used by Outlook Express External Firewall Configuration

  4. SCOofficeServer Firewall ActiveDirectoryServer 3268 Internal Firewall Configuration

  5. SCOoffice(master) SCOoffice(slave) SCOoffice(slave) Firewall 25389/636143/9932003 Internal Firewall Configuration

  6. SCOoffice(master) SCOoffice(slave) SCOoffice(slave) SCOoffice(slave) SCOoffice(slave) SCOoffice(slave) Firewall Internet 25389/636143/9932003 Remote Office Firewall Configuration

  7. SCO OpenServer’s HTTP Servers • SCO OpenServer runs HTTP servers on ports: • 80 – SCOoffice Server’s HTTP server • 443 – SCOoffice Server’s HTTPS server • 615 – Internet Configuration Manager • 8457 – DocView: Access to SCO OpenServer documentation

  8. Other SCOoffice Server Related Ports • SCOoffice Server runs daemons on ports: • 21 – ProFTP • 25 – SMTP • 110 – POP3 • 143 – IMAP • 389 – OpenLDAP • 993 – IMAP4 over TLS/SSL • 995 – POP3 over TLS/SSL • 2000 –Cyrusmaster (sieve) • 2003 –Cyrusmaster (LMTP) • 2583 – MON • 4840 – SASLAUTHD • 4844 – SASLAUTHD • 10024 – AMaViS

  9. Disallowing Open Relay • Don’t let server be used as an open relay • Numerous ways to prevent open relay • We will configure SASLAUTHD + TLS • # telnet rose.example.net smtp • 220 rose.example.net ESMTP Postfix (2.0.20) • HELO nuisance.spammer.net • 250 rose.example.net • MAIL FROM: nice_guy@example.net • 250 Ok • RCPT TO: victim@example.com • 250 Ok • ...

  10. Stored in LDAP Disallowing Open Relay • Useful for blocking unwanted SMTP sessions: • smtpd_client_restrictions • smtpd_sender_restrictions • smtpd_recipient_restrictions

  11. Disallowing Open Relay Simple Authentication and Security Layer (SASL) PLAIN authentication mechanismBase64 encoded:user+NULL+user+NULL+passwordbob\0\bob\0bpasswd LOGIN authentication mechanismBase64 encoded username bobBase64 encoded password bpasswd

  12. …/etc/imapd.conf sasl_pwcheck_method: saslauthd imapd/pop3d …/etc/cyrus.conf imap cmd=“imapd –p 2 …pop3 cmd=“pop3d” …… cyrusmaster Disallowing Open Relay SASL AUTHENTICATION …/etc/saslauthd.conf ldap_servers: ldap://127.0.0.1/ldap_filter: login=%u slapd saslauthd …/lib/sasl2/smtpd.conf pwcheck_method: saslauthdmech_list: plain login smtpd

  13. Disallowing Open Relay • SASL Configuration on the Server • smtpd_sasl_auth_enable = yes • smtpd_sender_restrictions = check_sender_access ldap:ldapSenderAccess, permit_sasl_authenticated • smtpd_recipient_restrictions =check_recipient_access ldap:ldapRecipientAccess, permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination • broken_sasl_auth_clients = yes • smtpd_sasl_security_options = noanonymous • smtpd_delay_reject = yes

  14. Disallowing Open Relay • SASL Configuration on the Client • smtp_sasl_auth_enable = yes • smtp_sasl_password_maps = hash:/opt/insight/etc/postfix/sasl_passwd • smtp_sasl_security_options = noanonymous

  15. Disallowing Open Relay • Create /opt/insight/etc/postfix/sasl_passwd: • Run postmap(1) after creating (or modifying) file example.net alice:apasswdexample.org bob:bpasswd

  16. Disallowing Open Relay • TLS v1 is based on SSL v3 • Encrypt SMTP traffic using TLS • X.509 certificates

  17. Disallowing Open Relay • TLS Configuration on the Server • smtpd_tls_cert_file = /opt/insight/etc/ssl/server.pem • smtpd_tls_key_file = /opt/insight/etc/ssl/server.pem • smtpd_tls_CAfile = /opt/insight/etc/ssl/server.pem • smtpd_use_tls = yes

  18. Disallowing Open Relay • TLS Configuration on the Client • smtp_tls_cert_file = /opt/insight/etc/ssl/server.pem • smtp_tls_key_file = /opt/insight/etc/ssl/server.pem • smtp_tls_CAfile = /opt/insight/etc/ssl/server.pem • smtp_use_tls = yes

  19. Disallowing Open Relay • Using a Certificate Authority’s Certificate • smtp_tls_CApath = /opt/insight/etc/ssl/ca_cert.pem • smtpd_tls_CApath = /opt/insight/etc/ssl/ca_cert.pem

  20. Disallowing Open Relay • To test to see if a mail server is an open relay: • Log into the mail server • telnet rt.njabl.org 2500

  21. Exercise: Tracing TLS and SASL SASL Authentication Only: TLS + SASL Authentication:

  22. Other Restrictions • Other useful restrictions: • smtpd_client_restrictions • smtpd_helo_restrictions • smtpd_sender_restrictions • See www.postfix.org/uce.html

  23. Using smtpd_client_restrictions • In main.cf: • In /opt/insight/etc/postfix/smtp_clients: smtpd_client_restrictions = check_client_access hash:/opt/insight/etc/postfix/smtp_clients, permit • 192.168.1.1 OK • 192.168.1.2 PERMIT • 192.168.1.3 REJECT • 192.168.1.123 REJECT • 192.168.1.0/24 OK • example.net OK • paper.example.org DUNNO • example.org REJECT

  24. Using smtpd_helo_restrictions • check_helo_access • reject_invalid_hostname • reject_non_fqdn_hostname • reject_unknown hostname • In main.cf: • In /opt/insight/etc/postfix/helo: smtpd_helo_restrictions = reject_invalid_hostname,check_helo_access hash:/opt/insight/etc/postfix/helo • example.org OK • example.net REJECT

  25. Using smtpd_sender_restrictions • check_sender_access • reject_unknown_sender_domain

  26. Creating a Chroot Jail • A chroot jail adds a layer of protection • Limits daemon(s) to /opt/insight/var/spool/postfix • Set the fifth field in master.cf to ‘y’

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