NAME
sudo_logsrvd — sudo event and I/O log server
SYNOPSIS
sudo_logsrvd [-hnV] [-f file] [-R percentage]
DESCRIPTION
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. The server has two modes of operation: local and relay. By default, sudo_logsrvd stores the logs locally but it can also be configured to relay them to another server that supports the sudo_logsrv.proto(5) protocol.
When not relaying, event log entries may be logged either via syslog(3) or to a local file. I/O Logs stored locally 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 distinguish 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 or the file specified via the -f option.
sudo_logsrvd rereads its configuration file when it receives SIGHUP and writes server state to the debug file (if one is configured) when it receives SIGUSR1.
The options are as follows:
-f file, --file=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 percentage, --random-drop=percentage
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 certificate 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), refer to its manual.
FILES
/etc/sudo.conf
Sudo front-end configuration
/etc/sudo_logsrvd.conf
Sudo log server configuration file
/var/log/sudo_logsrvd/incoming
Directory where new journals are stored when the store_first relay setting is enabled.
/var/log/sudo_logsrvd/outgoing
Directory where completed journals are stored when the store_first relay setting is enabled.
/var/log/sudo-io
Default I/O log file location
/run/sudo/sudo_logsrvd.pid
Process ID file for sudo_logsrvd
EXAMPLES
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 certificates.
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”, “CA_default”, “v3_ca”, and “usr_cert” sections. Those sections should include at least 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
[ v3_ca ]
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer
basicConstraints = critical,CA:true
keyUsage = cRLSign, keyCertSign
[ usr_cert ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, \
keyEncipherment
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
If your openssl.conf file already has a “CA_default” section, you may only need to modify the “dir” setting and enable the “keyUsage” settings if they are commented out.
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 certificates 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 certificate. 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
X509v3 Key Usage:
Digital Signature, Non Repudiation, Key Encipherment
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 different 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:
# Listen on
port 30344 for TLS connections to any address.
listen_address = *:30344(tls)
# 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.
SEE ALSO
sudo.conf(5), sudo_logsrvd.conf(5), sudoers(5), sudo(8), sudo_sendlog(8), sudoreplay(8)
AUTHORS
Many people have worked on sudo over the years; this version consists of code written primarily by:
Todd C. Miller
See the CONTRIBUTORS.md file in the sudo distribution (https://www.sudo.ws/about/contributors/) for an exhaustive list of people who have contributed to sudo.
BUGS
If you believe you have found a bug in sudo_logsrvd, you can submit a bug report at https://bugzilla.sudo.ws/
SUPPORT
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.
DISCLAIMER
sudo_logsrvd is provided “AS IS” and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE.md file distributed with sudo or https://www.sudo.ws/about/license/ for complete details.
Sudo 1.9.15p5 January 16, 2023 Sudo 1.9.15p5