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SUDO_LOGSRVD(8) BSD System Manager's Manual SUDO_LOGSRVD(8)
sudo_logsrvd — sudo event and I/O log server
sudo_logsrvd [-hnV] [-f file] [-R percentage]
sudo_logsrvd is a high-performance log server that accepts event and
I/O logs from sudo. It can be used to implement centralized logging of
sudo logs. Event log entries may be logged either via syslog(3) or to
a file. I/O Logs created by sudo_logsrvd can be replayed via the
sudoreplay(8) utility in the same way as logs generated directly by the
sudoers plugin.
The server also supports restarting interrupted log transfers. To dis‐
tinguish completed I/O logs from incomplete ones, the I/O log timing
file is set to be read-only when the log is complete.
Configuration parameters for sudo_logsrvd may be specified in the
sudo_logsrvd.conf(5) file.
The options are as follows:
-f, --file Read configuration from file instead of the default,
/etc/sudo_logsrvd.conf.
-h, --help Display a short help message to the standard output and
exit.
-n, --no-fork
Run sudo_logsrvd in the foreground instead of detaching
from the terminal and becoming a daemon.
-R, --random-drop
For each message, there is a percentage chance that the
server will drop the connection. This is only intended for
debugging the ability of a client to restart a connection.
-V, --version
Print the sudo_logsrvd version and exit.
Securing server connections
The I/O log data sent to sudo_logsrvd may contain sensitive information
such as passwords and should be secured using Transport Layer Security
(TLS). Doing so requires having a signed certificate on the server
and, if tls_checkpeer is enabled in sudo_logsrvd.conf(5), a signed cer‐
tificate on the client as well.
The certificates can either be signed by a well-known Certificate
Authority (CA), or a private CA can be used. Instructions for creating
a private CA are included below in the EXAMPLES section.
Debugging sudo_logsrvd
sudo_logsrvd supports a flexible debugging framework that is configured
via Debug lines in the sudo.conf(5) file.
For more information on configuring sudo.conf(5), please refer to its
manual.
/etc/sudo.conf Sudo front end configuration
/etc/sudo_logsrvd.conf Sudo log server configuration file
/var/log/sudo-io Default I/O log file location
/sudo/sudo_logsrvd.pid Process ID file for sudo_logsrvd
Creating self-signed certificates
Unless you are using certificates signed by a well-known Certificate
Authority (or a local enterprise CA), you will need to create your own
CA that can sign the certificates used by sudo_logsrvd, sudo_sendlog,
and the sudoers plugin. The following steps use the openssl(1) command
to create keys and certificates.
Initial setup
First, we need to create a directory structure to store the files for
the CA. We'll create a new directory hierarchy in /etc/ssl/sudo for
this purpose.
# mkdir /etc/ssl/sudo
# cd /etc/ssl/sudo
# mkdir certs csr newcerts private
# chmod 700 private
# touch index.txt
# echo 1000 > serial
The serial and index.txt files are used to keep track of signed cer‐
tificates.
Next, we need to make a copy of the openssl.conf file and customize it
for our new CA. The path to openssl.cnf is system-dependent but
/etc/ssl/openssl.cnf is the most common location. You will need to
adjust the example below if it has a different location on your system.
# cp /etc/ssl/openssl.cnf .
Now edit the openssl.cnf file in the current directory and make sure it
contains “ca” and “CA_default” sections. Those sections should include
the following settings:
[ ca ]
default_ca = CA_default
[ CA_default ]
dir = /etc/ssl/sudo
certs = $dir/certs
database = $dir/index.txt
certificate = $dir/cacert.pem
serial = $dir/serial
If your openssl.conf file already has a “CA_default” section, you may
only need to modify the “dir” setting.
Creating the CA key and certificate
In order to create and sign our own certificates, we need to create a
private key and a certificate for the root of the CA. First, create
the private key and protect it with a pass phrase:
# openssl genrsa -aes256 -out private/cakey.pem 4096
# chmod 400 private/cakey.pem
Next, generate the root certificate, using appropriate values for the
site-specific fields:
# openssl req -config openssl.cnf -key private/cakey.pem \
-new -x509 -days 7300 -sha256 -extensions v3_ca \
-out cacert.pem
Enter pass phrase for private/cakey.pem:
You are about to be asked to enter information that will be
incorporated into your certificate request.
What you are about to enter is what is called a Distinguished Name
or a DN.
There are quite a few fields but you can leave some blank.
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:Colorado
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:sudo
Organizational Unit Name (eg, section) []:sudo Certificate Authority
Common Name (e.g., server FQDN or YOUR name) []:sudo Root CA
Email Address []:
# chmod 444 cacert.pem
Finally, verify the root certificate:
# openssl x509 -noout -text -in cacert.pem
Creating and signing certificates
The server and client certificates will be signed by the previously
created root CA. Usually, the root CA is not used to sign
server/client certificates directly. Instead, intermediate certifi‐
cates are created and signed with the root CA and the intermediate
certs are used to sign CSRs (Certificate Signing Request). In this
example we'll skip this part for simplicity's sake and sign the CSRs
with the root CA.
First, generate the private key without a pass phrase.
# openssl genrsa -out private/logsrvd_key.pem 2048
# chmod 400 private/logsrvd_key.pem
Next, create a certificate signing request (CSR) for the server's cer‐
tificate. The organization name must match the name given in the root
certificate. The common name should be either the server's IP address
or a fully qualified domain name.
# openssl req -config openssl.cnf -key private/logsrvd_key.pem -new \
-sha256 -out csr/logsrvd_csr.pem
Enter pass phrase for private/logsrvd_key.pem:
You are about to be asked to enter information that will be
incorporated into your certificate request.
What you are about to enter is what is called a Distinguished Name
or a DN.
There are quite a few fields but you can leave some blank.
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:US
State or Province Name (full name) [Some-State]:Colorado
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:sudo
Organizational Unit Name (eg, section) []:sudo log server
Common Name (e.g., server FQDN or YOUR name) []:logserver.example.com
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Now sign the CSR that was just created:
# openssl ca -config openssl.cnf -days 375 -notext -md sha256 \
-in csr/logsrvd_csr.pem -out certs/logsrvd_cert.pem
Using configuration from openssl.cnf
Enter pass phrase for ./private/cakey.pem:
Check that the request matches the signature
Signature ok
Certificate Details:
Serial Number: 4096 (0x1000)
Validity
Not Before: Nov 11 14:05:05 2019 GMT
Not After : Nov 20 14:05:05 2020 GMT
Subject:
countryName = US
stateOrProvinceName = Colorado
organizationName = sudo
organizationalUnitName = sudo log server
commonName = logserve.example.com
X509v3 extensions:
X509v3 Basic Constraints:
CA:FALSE
Netscape Comment:
OpenSSL Generated Certificate
X509v3 Subject Key Identifier:
4C:50:F9:D0:BE:1A:4C:B2:AC:90:76:56:C7:9E:16:AE:E6:9E:E5:B5
X509v3 Authority Key Identifier:
keyid:D7:91:24:16:B1:03:06:65:1A:7A:6E:CF:51:E9:5C:CB:7A:95:3E:0C
Certificate is to be certified until Nov 20 14:05:05 2020 GMT (375 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
Finally, verify the new certificate:
# openssl verify -CAfile cacert.pem certs/logsrvd_cert.pem
certs/logsrvd_cert.pem: OK
The /etc/ssl/sudo/certs directory now contains a signed and verified
certificate for use with sudo_logsrvd.
To generate a client certificate, repeat the process above using a dif‐
ferent file name.
Configuring sudo_logsrvd to use TLS
To use TLS for client/server communication, both sudo_logsrvd and the
sudoers plugin need to be configured to use TLS. Configuring
sudo_logsrvd for TLS requires the following settings, assuming the same
path names used earlier:
# If set, secure connections with TLS 1.2 or 1.3.
tls = true
# Path to the certificate authority bundle file in PEM format.
tls_cacert = /etc/ssl/sudo/cacert.pem
# Path to the server's certificate file in PEM format.
tls_cert = /etc/ssl/sudo/certs/logsrvd_cert.pem
# Path to the server's private key file in PEM format.
tls_key = /etc/ssl/sudo/private/logsrvd_key.pem
The root CA cert (cacert.pem) must be installed on the system running
sudo_logsrvd. If peer authentication is enabled on the client, a copy
of cacert.pem must be present on the client system too.
sudo.conf(5), sudo_logsrvd.conf(5), sudoers(5), sudo(8),
sudo_sendlog(8), sudoreplay(8)
Many people have worked on sudo over the years; this version consists
of code written primarily by:
Todd C. Miller
See the CONTRIBUTORS file in the sudo distribution
(https://www.sudo.ws/contributors.html) for an exhaustive list of peo‐
ple who have contributed to sudo.
If you feel you have found a bug in sudo_logsrvd, please submit a bug
report at https://bugzilla.sudo.ws/
Limited free support is available via the sudo-users mailing list, see
https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
the archives.
sudo_logsrvd is provided “AS IS” and any express or implied warranties,
including, but not limited to, the implied warranties of merchantabil‐
ity and fitness for a particular purpose are disclaimed. See the
LICENSE file distributed with sudo or https://www.sudo.ws/license.html
for complete details.
This page is part of the sudo (execute a command as another user)
project. Information about the project can be found at
https://www.sudo.ws/. If you have a bug report for this manual page,
see ⟨https://bugzilla.sudo.ws/⟩. This page was obtained from the
project's upstream Git repository
⟨https://github.com/sudo-project/sudo⟩ on 2020-08-13. (At that time,
the date of the most recent commit that was found in the repository was
2020-08-12.) If you discover any rendering problems in this HTML ver‐
sion of the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original manual
page), send a mail to man-pages@man7.org
Sudo 1.9.2 March 28, 2020 Sudo 1.9.2