{
    "mode": "man",
    "parameter": "TLSPROXY",
    "section": "8postfix",
    "url": "https://www.chedong.com/phpMan.php/man/TLSPROXY/8postfix/json",
    "generated": "2026-10-06T12:52:25Z",
    "synopsis": "tlsproxy [generic Postfix daemon options]",
    "sections": {
        "NAME": {
            "content": "tlsproxy - Postfix TLS proxy\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "tlsproxy [generic Postfix daemon options]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "The tlsproxy(8) server implements a two-way TLS proxy. It is used by the postscreen(8) server\nto  talk  SMTP-over-TLS  with remote SMTP clients that are not allowlisted (including clients\nwhose allowlist status has expired), and by the smtp(8)  client  to  support  TLS  connection\nreuse, but it should also work for non-SMTP protocols.\n\nAlthough  one  tlsproxy(8) process can serve multiple sessions at the same time, it is a good\nidea to allow the number of processes to increase with load, so that the service remains  re‐\nsponsive.\n",
            "subsections": []
        },
        "PROTOCOL EXAMPLE": {
            "content": "The  example below concerns postscreen(8). However, the tlsproxy(8) server is agnostic of the\napplication protocol, and the example is easily adapted to other applications.\n\nAfter receiving a valid remote SMTP client STARTTLS command, the postscreen(8)  server  sends\nthe  remote SMTP client endpoint string, the requested role (server), and the requested time‐\nout to tlsproxy(8).  postscreen(8) then  receives  a  \"TLS  available\"  indication  from  tl‐\nsproxy(8).   If the TLS service is available, postscreen(8) sends the remote SMTP client file\ndescriptor to tlsproxy(8), and sends the plaintext 220 greeting to the  remote  SMTP  client.\nThis  triggers TLS negotiations between the remote SMTP client and tlsproxy(8).  Upon comple‐\ntion of the TLS-level handshake,  tlsproxy(8)  translates  between  plaintext  from/to  post‐\nscreen(8) and ciphertext to/from the remote SMTP client.\n",
            "subsections": []
        },
        "SECURITY": {
            "content": "The  tlsproxy(8)  server  is moderately security-sensitive.  It talks to untrusted clients on\nthe network. The process can be run chrooted at fixed low privilege.\n",
            "subsections": []
        },
        "DIAGNOSTICS": {
            "content": "Problems and transactions are logged to syslogd(8) or postlogd(8).\n",
            "subsections": []
        },
        "CONFIGURATION PARAMETERS": {
            "content": "Changes to main.cf are not picked up automatically, as tlsproxy(8) processes may  run  for  a\nlong  time  depending  on  mail  server load.  Use the command \"postfix reload\" to speed up a\nchange.\n\nThe text below provides only a parameter summary. See postconf(5) for more details  including\nexamples.\n",
            "subsections": []
        },
        "STARTTLS GLOBAL CONTROLS": {
            "content": "The  following settings are global and therefore cannot be overruled by information specified\nin a tlsproxy(8) client request.\n",
            "subsections": [
                {
                    "name": "tls_append_default_CA (no)",
                    "content": "Append the system-supplied default Certification Authority certificates  to  the  ones\nspecified with *tlsCApath or *tlsCAfile.\n"
                },
                {
                    "name": "tls_daemon_random_bytes (32)",
                    "content": "The  number  of  pseudo-random bytes that an smtp(8) or smtpd(8) process requests from\nthe tlsmgr(8) server in order to seed its  internal  pseudo  random  number  generator\n(PRNG).\n"
                },
                {
                    "name": "tls_high_cipherlist (see 'postconf -d' output)",
                    "content": "The OpenSSL cipherlist for \"high\" grade ciphers.\n"
                },
                {
                    "name": "tls_medium_cipherlist (see 'postconf -d' output)",
                    "content": "The OpenSSL cipherlist for \"medium\" or higher grade ciphers.\n"
                },
                {
                    "name": "tls_null_cipherlist (eNULL:!aNULL)",
                    "content": "The  OpenSSL  cipherlist  for \"NULL\" grade ciphers that provide authentication without\nencryption.\n"
                },
                {
                    "name": "tls_eecdh_strong_curve (prime256v1)",
                    "content": "The elliptic curve used by the Postfix SMTP server for sensibly strong ephemeral  ECDH\nkey exchange.\n"
                },
                {
                    "name": "tls_eecdh_ultra_curve (secp384r1)",
                    "content": "The elliptic curve used by the Postfix SMTP server for maximally strong ephemeral ECDH\nkey exchange.\n"
                },
                {
                    "name": "tls_disable_workarounds (see 'postconf -d' output)",
                    "content": "List or bit-mask of OpenSSL bug work-arounds to disable.\n"
                },
                {
                    "name": "tls_preempt_cipherlist (no)",
                    "content": "With SSLv3 and later, use the Postfix SMTP server's cipher preference order instead of\nthe remote client's cipher preference order.\n\nAvailable in Postfix version 2.8..3.7:\n"
                },
                {
                    "name": "tls_low_cipherlist (see 'postconf -d' output)",
                    "content": "The OpenSSL cipherlist for \"low\" or higher grade ciphers.\n"
                },
                {
                    "name": "tls_export_cipherlist (see 'postconf -d' output)",
                    "content": "The OpenSSL cipherlist for \"export\" or higher grade ciphers.\n\nAvailable in Postfix version 2.9 and later:\n"
                },
                {
                    "name": "tls_legacy_public_key_fingerprints (no)",
                    "content": "A  temporary migration aid for sites that use certificate public-key fingerprints with\nPostfix 2.9.0..2.9.5, which use an incorrect algorithm.\n\nAvailable in Postfix version 2.11-3.1:\n"
                },
                {
                    "name": "tls_dane_digest_agility (on)",
                    "content": "Configure RFC7671 DANE TLSA digest algorithm agility.\n"
                },
                {
                    "name": "tls_dane_trust_anchor_digest_enable (yes)",
                    "content": "Enable support for RFC 6698 (DANE TLSA) DNS records that contain digests of  trust-an‐\nchors with certificate usage \"2\".\n\nAvailable in Postfix version 2.11 and later:\n"
                },
                {
                    "name": "tlsmgr_service_name (tlsmgr)",
                    "content": "The name of the tlsmgr(8) service entry in master.cf.\n\nAvailable in Postfix version 3.0 and later:\n"
                },
                {
                    "name": "tls_session_ticket_cipher (Postfix >= 3.0: aes-256-cbc, Postfix < 3.0: aes-128-cbc)",
                    "content": "Algorithm used to encrypt RFC5077 TLS session tickets.\n"
                },
                {
                    "name": "openssl_path (openssl)",
                    "content": "The location of the OpenSSL command line program openssl(1).\n\nAvailable in Postfix version 3.2 and later:\n"
                },
                {
                    "name": "tls_eecdh_auto_curves (see 'postconf -d' output)",
                    "content": "The  prioritized  list  of  elliptic  curves  supported by the Postfix SMTP client and\nserver.\n\nAvailable in Postfix version 3.4 and later:\n"
                },
                {
                    "name": "tls_server_sni_maps (empty)",
                    "content": "Optional lookup tables that map names received from remote SMTP clients  via  the  TLS\nServer Name Indication (SNI) extension to the appropriate keys and certificate chains.\n\nAvailable in Postfix 3.5, 3.4.6, 3.3.5, 3.2.10, 3.1.13 and later:\n"
                },
                {
                    "name": "tls_fast_shutdown_enable (yes)",
                    "content": "A  workaround for implementations that hang Postfix while shutting down a TLS session,\nuntil Postfix times out.\n\nAvailable in Postfix version 3.8 and later:\n"
                },
                {
                    "name": "tls_ffdhe_auto_groups (see 'postconf -d' output)",
                    "content": "The prioritized list of finite-field Diffie-Hellman  ephemeral  (FFDHE)  key  exchange\ngroups supported by the Postfix SMTP client and server.\n\nAvailable in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later:\n"
                },
                {
                    "name": "tls_config_file (default)",
                    "content": "Optional configuration file with baseline OpenSSL settings.\n"
                },
                {
                    "name": "tls_config_name (empty)",
                    "content": "The application name passed by Postfix to OpenSSL library initialization functions.\n"
                }
            ]
        },
        "STARTTLS SERVER CONTROLS": {
            "content": "These  settings  are  clones of Postfix SMTP server settings.  They allow tlsproxy(8) to load\nthe same certificate and private key information as the Postfix SMTP server, before  dropping\nprivileges,  so  that  the  key files can be kept read-only for root. These settings can cur‐\nrently not be overruled by information in a tlsproxy(8) client request, but  that  limitation\nmay be removed in a future version.\n",
            "subsections": [
                {
                    "name": "tlsproxy_tls_CAfile ($smtpd_tls_CAfile)",
                    "content": "A  file containing (PEM format) CA certificates of root CAs trusted to sign either re‐\nmote SMTP client certificates or intermediate CA certificates.\n"
                },
                {
                    "name": "tlsproxy_tls_CApath ($smtpd_tls_CApath)",
                    "content": "A directory containing (PEM format) CA certificates of root CAs trusted to sign either\nremote SMTP client certificates or intermediate CA certificates.\n"
                },
                {
                    "name": "tlsproxy_tls_always_issue_session_ids ($smtpd_tls_always_issue_session_ids)",
                    "content": "Force the Postfix tlsproxy(8) server to issue a TLS session id, even when TLS  session\ncaching is turned off.\n"
                },
                {
                    "name": "tlsproxy_tls_ask_ccert ($smtpd_tls_ask_ccert)",
                    "content": "Ask a remote SMTP client for a client certificate.\n"
                },
                {
                    "name": "tlsproxy_tls_ccert_verifydepth ($smtpd_tls_ccert_verifydepth)",
                    "content": "The verification depth for remote SMTP client certificates.\n"
                },
                {
                    "name": "tlsproxy_tls_cert_file ($smtpd_tls_cert_file)",
                    "content": "File with the Postfix tlsproxy(8) server RSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_ciphers ($smtpd_tls_ciphers)",
                    "content": "The  minimum TLS cipher grade that the Postfix tlsproxy(8) server will use with oppor‐\ntunistic TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_tls_dcert_file ($smtpd_tls_dcert_file)",
                    "content": "File with the Postfix tlsproxy(8) server DSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_dh1024_param_file ($smtpd_tls_dh1024_param_file)",
                    "content": "File with DH parameters that the Postfix tlsproxy(8) server should use with non-export\nEDH ciphers.\n"
                },
                {
                    "name": "tlsproxy_tls_dh512_param_file ($smtpd_tls_dh512_param_file)",
                    "content": "File with DH parameters that the  Postfix  tlsproxy(8)  server  should  use  with  ex‐\nport-grade EDH ciphers.\n"
                },
                {
                    "name": "tlsproxy_tls_dkey_file ($smtpd_tls_dkey_file)",
                    "content": "File with the Postfix tlsproxy(8) server DSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_eccert_file ($smtpd_tls_eccert_file)",
                    "content": "File with the Postfix tlsproxy(8) server ECDSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_eckey_file ($smtpd_tls_eckey_file)",
                    "content": "File with the Postfix tlsproxy(8) server ECDSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_eecdh_grade ($smtpd_tls_eecdh_grade)",
                    "content": "The   Postfix   tlsproxy(8)   server   security  grade  for  ephemeral  elliptic-curve\nDiffie-Hellman (EECDH) key exchange.\n"
                },
                {
                    "name": "tlsproxy_tls_exclude_ciphers ($smtpd_tls_exclude_ciphers)",
                    "content": "List of ciphers or cipher types to exclude from the tlsproxy(8) server cipher list  at\nall TLS security levels.\n"
                },
                {
                    "name": "tlsproxy_tls_fingerprint_digest ($smtpd_tls_fingerprint_digest)",
                    "content": "The message digest algorithm to construct remote SMTP client-certificate fingerprints.\n"
                },
                {
                    "name": "tlsproxy_tls_key_file ($smtpd_tls_key_file)",
                    "content": "File with the Postfix tlsproxy(8) server RSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_tls_loglevel ($smtpd_tls_loglevel)",
                    "content": "Enable additional Postfix tlsproxy(8) server logging of TLS activity.\n"
                },
                {
                    "name": "tlsproxy_tls_mandatory_ciphers ($smtpd_tls_mandatory_ciphers)",
                    "content": "The  minimum TLS cipher grade that the Postfix tlsproxy(8) server will use with manda‐\ntory TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_tls_mandatory_exclude_ciphers ($smtpd_tls_mandatory_exclude_ciphers)",
                    "content": "Additional list of ciphers or cipher types to exclude from the tlsproxy(8) server  ci‐\npher list at mandatory TLS security levels.\n"
                },
                {
                    "name": "tlsproxy_tls_mandatory_protocols ($smtpd_tls_mandatory_protocols)",
                    "content": "The  SSL/TLS  protocols  accepted by the Postfix tlsproxy(8) server with mandatory TLS\nencryption.\n"
                },
                {
                    "name": "tlsproxy_tls_protocols ($smtpd_tls_protocols)",
                    "content": "List of TLS protocols that the Postfix tlsproxy(8) server will exclude or include with\nopportunistic TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_tls_req_ccert ($smtpd_tls_req_ccert)",
                    "content": "With mandatory TLS encryption, require a trusted remote SMTP client certificate in or‐\nder to allow TLS connections to proceed.\n"
                },
                {
                    "name": "tlsproxy_tls_security_level ($smtpd_tls_security_level)",
                    "content": "The SMTP TLS security level for the Postfix tlsproxy(8) server; when a non-empty value\nis specified, this overrides  the  obsolete  parameters  smtpdusetls  and  smtpden‐\nforcetls.\n"
                },
                {
                    "name": "tlsproxy_tls_chain_files ($smtpd_tls_chain_files)",
                    "content": "Files with the Postfix tlsproxy(8) server keys and certificate chains in PEM format.\n"
                }
            ]
        },
        "STARTTLS CLIENT CONTROLS": {
            "content": "These  settings  are  clones of Postfix SMTP client settings.  They allow tlsproxy(8) to load\nthe same certificate and private key information as the Postfix SMTP client, before  dropping\nprivileges,  so that the key files can be kept read-only for root. Some settings may be over‐\nruled by information in a tlsproxy(8) client request.\n\nAvailable in Postfix version 3.4 and later:\n",
            "subsections": [
                {
                    "name": "tlsproxy_client_CAfile ($smtp_tls_CAfile)",
                    "content": "A file containing CA certificates of root CAs trusted to sign either remote TLS server\ncertificates or intermediate CA certificates.\n"
                },
                {
                    "name": "tlsproxy_client_CApath ($smtp_tls_CApath)",
                    "content": "Directory with PEM format Certification Authority certificates that  the  Postfix  tl‐\nsproxy(8) client uses to verify a remote TLS server certificate.\n"
                },
                {
                    "name": "tlsproxy_client_chain_files ($smtp_tls_chain_files)",
                    "content": "Files with the Postfix tlsproxy(8) client keys and certificate chains in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_cert_file ($smtp_tls_cert_file)",
                    "content": "File with the Postfix tlsproxy(8) client RSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_key_file ($smtp_tls_key_file)",
                    "content": "File with the Postfix tlsproxy(8) client RSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_dcert_file ($smtp_tls_dcert_file)",
                    "content": "File with the Postfix tlsproxy(8) client DSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_dkey_file ($smtp_tls_dkey_file)",
                    "content": "File with the Postfix tlsproxy(8) client DSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_eccert_file ($smtp_tls_eccert_file)",
                    "content": "File with the Postfix tlsproxy(8) client ECDSA certificate in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_eckey_file ($smtp_tls_eckey_file)",
                    "content": "File with the Postfix tlsproxy(8) client ECDSA private key in PEM format.\n"
                },
                {
                    "name": "tlsproxy_client_fingerprint_digest ($smtp_tls_fingerprint_digest)",
                    "content": "The  message  digest algorithm used to construct remote TLS server certificate finger‐\nprints.\n"
                },
                {
                    "name": "tlsproxy_client_loglevel ($smtp_tls_loglevel)",
                    "content": "Enable additional Postfix tlsproxy(8) client logging of TLS activity.\n"
                },
                {
                    "name": "tlsproxy_client_loglevel_parameter (smtp_tls_loglevel)",
                    "content": "The name of the parameter that provides the tlsproxyclientloglevel value.\n"
                },
                {
                    "name": "tlsproxy_client_scert_verifydepth ($smtp_tls_scert_verifydepth)",
                    "content": "The verification depth for remote TLS server certificates.\n"
                },
                {
                    "name": "tlsproxy_client_use_tls ($smtp_use_tls)",
                    "content": "Opportunistic mode: use TLS when a remote server announces TLS support.\n"
                },
                {
                    "name": "tlsproxy_client_enforce_tls ($smtp_enforce_tls)",
                    "content": "Enforcement mode: require that SMTP servers use TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_client_per_site ($smtp_tls_per_site)",
                    "content": "Optional lookup tables with  the  Postfix  tlsproxy(8)  client  TLS  usage  policy  by\nnext-hop destination and by remote TLS server hostname.\n\nAvailable in Postfix version 3.4-3.6:\n"
                },
                {
                    "name": "tlsproxy_client_level ($smtp_tls_security_level)",
                    "content": "The default TLS security level for the Postfix tlsproxy(8) client.\n"
                },
                {
                    "name": "tlsproxy_client_policy ($smtp_tls_policy_maps)",
                    "content": "Optional  lookup  tables  with  the  Postfix tlsproxy(8) client TLS security policy by\nnext-hop destination.\n\nAvailable in Postfix version 3.7 and later:\n"
                },
                {
                    "name": "tlsproxy_client_security_level ($smtp_tls_security_level)",
                    "content": "The default TLS security level for the Postfix tlsproxy(8) client.\n"
                },
                {
                    "name": "tlsproxy_client_policy_maps ($smtp_tls_policy_maps)",
                    "content": "Optional lookup tables with the Postfix tlsproxy(8)  client  TLS  security  policy  by\nnext-hop destination.\n"
                }
            ]
        },
        "OBSOLETE STARTTLS SUPPORT CONTROLS": {
            "content": "These parameters are supported for compatibility with smtpd(8) legacy parameters.\n",
            "subsections": [
                {
                    "name": "tlsproxy_use_tls ($smtpd_use_tls)",
                    "content": "Opportunistic  TLS:  announce  STARTTLS support to remote SMTP clients, but do not re‐\nquire that clients use TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_enforce_tls ($smtpd_enforce_tls)",
                    "content": "Mandatory TLS: announce STARTTLS support to remote  SMTP  clients,  and  require  that\nclients use TLS encryption.\n"
                },
                {
                    "name": "tlsproxy_client_use_tls ($smtp_use_tls)",
                    "content": "Opportunistic mode: use TLS when a remote server announces TLS support.\n"
                },
                {
                    "name": "tlsproxy_client_enforce_tls ($smtp_enforce_tls)",
                    "content": "Enforcement mode: require that SMTP servers use TLS encryption.\n"
                }
            ]
        },
        "RESOURCE CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "tlsproxy_watchdog_timeout (10s)",
                    "content": "How  much time a tlsproxy(8) process may take to process local or remote I/O before it\nis terminated by a built-in watchdog timer.\n"
                }
            ]
        },
        "MISCELLANEOUS CONTROLS": {
            "content": "",
            "subsections": [
                {
                    "name": "config_directory (see 'postconf -d' output)",
                    "content": "The default location of the Postfix main.cf and master.cf configuration files.\n"
                },
                {
                    "name": "process_id (read-only)",
                    "content": "The process ID of a Postfix command or daemon process.\n"
                },
                {
                    "name": "process_name (read-only)",
                    "content": "The process name of a Postfix command or daemon process.\n"
                },
                {
                    "name": "syslog_facility (mail)",
                    "content": "The syslog facility of Postfix logging.\n"
                },
                {
                    "name": "syslog_name (see 'postconf -d' output)",
                    "content": "A prefix that is prepended to the process name in syslog records, so that,  for  exam‐\nple, \"smtpd\" becomes \"prefix/smtpd\".\n\nAvailable in Postfix 3.3 and later:\n"
                },
                {
                    "name": "service_name (read-only)",
                    "content": "The master.cf service name of a Postfix daemon process.\n"
                }
            ]
        },
        "SEE ALSO": {
            "content": "postscreen(8), Postfix zombie blocker\nsmtpd(8), Postfix SMTP server\npostconf(5), configuration parameters\npostlogd(8), Postfix logging\nsyslogd(8), system logging\n",
            "subsections": []
        },
        "LICENSE": {
            "content": "The Secure Mailer license must be distributed with this software.\n",
            "subsections": []
        },
        "HISTORY": {
            "content": "This service was introduced with Postfix version 2.8.\n\nAUTHOR(S)\nWietse Venema\nIBM T.J. Watson Research\nP.O. Box 704\nYorktown Heights, NY 10598, USA\n\nWietse Venema\nGoogle, Inc.\n111 8th Avenue\nNew York, NY 10011, USA\n\nTLSPROXY(8postfix)",
            "subsections": []
        }
    },
    "summary": "tlsproxy - Postfix TLS proxy",
    "flags": [],
    "examples": [],
    "see_also": [
        {
            "name": "postscreen",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/postscreen/8/json"
        },
        {
            "name": "smtpd",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/smtpd/8/json"
        },
        {
            "name": "postconf",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/postconf/5/json"
        },
        {
            "name": "postlogd",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/postlogd/8/json"
        },
        {
            "name": "syslogd",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/syslogd/8/json"
        }
    ]
}