OPENSSL-SESS_ID(1SSL) OpenSSL OPENSSL-SESS_ID(1SSL)
NAME
openssl-sess_id - SSL/TLS session handling command
SYNOPSIS
openssl sess_id [-help] [-inform DER|PEM] [-outform DER|PEM|NSS] [-in
filename] [-out filename] [-text] [-cert] [-noout] [-context ID]
DESCRIPTION
This command processes the encoded version of the SSL session structure
and optionally prints out SSL session details (for example the SSL
session master key) in human readable format. Since this is a diagnostic
tool that needs some knowledge of the SSL protocol to use properly, most
users will not need to use it.
The precise format of the data can vary across OpenSSL versions and is
not documented.
OPTIONS
-help
Print out a usage message.
-inform DER|PEM, -outform DER|PEM|NSS
The input and output formats; the default is PEM. See
openssl-format-options(1) for details.
For NSS output, the session ID and master key are reported in NSS
"keylog" format.
-in filename
This specifies the input filename to read session information from
or standard input by default.
-out filename
This specifies the output filename to write session information to
or standard output if this option is not specified.
-text
Prints out the various public or private key components in plain
text in addition to the encoded version.
-cert
If a certificate is present in the session it will be output using
this option, if the -text option is also present then it will be
printed out in text form.
-noout
This option prevents output of the encoded version of the session.
-context ID
This option can set the session id so the output session information
uses the supplied ID. The ID can be any string of characters. This
option won't normally be used.
OUTPUT
Typical output:
SSL-Session:
Protocol : TLSv1
Cipher : 0016
Session-ID: 871E62626C554CE95488823752CBD5F3673A3EF3DCE9C67BD916C809914B40ED
Session-ID-ctx: 01000000
Master-Key: A7CEFC571974BE02CAC305269DC59F76EA9F0B180CB6642697A68251F2D2BB57E51DBBB4C7885573192AE9AEE220FACD
Key-Arg : None
Start Time: 948459261
Timeout : 300 (sec)
Verify return code 0 (ok)
These are described below in more detail.
Protocol
This is the protocol in use TLSv1.3, TLSv1.2, TLSv1.1, TLSv1 or
SSLv3.
Cipher
The cipher used this is the actual raw SSL or TLS cipher code, see
the SSL or TLS specifications for more information.
Session-ID
The SSL session ID in hex format.
Session-ID-ctx
The session ID context in hex format.
Master-Key
This is the SSL session master key.
Start Time
This is the session start time represented as an integer in standard
Unix format.
Timeout
The timeout in seconds.
Verify return code
This is the return code when an SSL client certificate is verified.
NOTES
Since the SSL session output contains the master key it is possible to
read the contents of an encrypted session using this information.
Therefore, appropriate security precautions should be taken if the
information is being output by a "real" application. This is however
strongly discouraged and should only be used for debugging purposes.
BUGS
The cipher and start time should be printed out in human readable form.
SEE ALSO
openssl(1), openssl-ciphers(1), openssl-s_server(1)
COPYRIGHT
Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.5.4 2025-09-30 OPENSSL-SESS_ID(1SSL)
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