Enabling SSL/TLS Sessions In PgBouncer

Enabling SSL:TLS Sessions In PgBouncer PgBouncer is a great piece of technology! Over the years I’ve put it to good use in any number of situations requiring a particular type of control over application processes connecting to a postgres data cluster. However, sometimes it’s been a bit of a challenge when it comes to configuration.

Today, I want to demonstrate one way of conducting a connection session using the Secure Socket Layer, SSL/TLS.

For our purposes we’re going to make the following assumptions:

We are using a typical installation found on CENTOS-7.
PostgreSQL version 13 is used, but essentially any currently supported version of postgres will work.

Here are the steps enabling SSL connection sessions:

Setup postgres
- install RPM packages
- setup remote access
- create a ROLE with remote login privileges
Setup pgbouncer
- install RPM packages
- setup the minimal configuration permitting remote login without SSL
Generate SSL/TSL private keys and certificates
- TLS certificate for postgres
- TLS certificate for pgbouncer
- Create a Certificate Authority (CA) capable of signing the aforementioned certificates
Configure for SSL encrypted sessions
1. postgres
2. pgbouncer

Step 1: Setup Postgres

Setting up your postgres server is straightforward:

Add the appropriate repository for postgres version 13.

Shell

yum install openssl
yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
yum update -y
yum install -y postgresql13-server
The datacluster is initialized.

Shell

/usr/pgsql-12/bin/postgresql-12-setup initdb
The datacluster configuration files “pg_hba.conf” and “postgresql.auto.conf” are edited. Note that both IPv4 and IPv6 protocols have been configured.

Shell

echo "
##############################################################
#PG_HBA.CONF
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all trust
# IPv4 local connections:
host all all 127.0.0.1/32 md5
host all all 0.0.0.0/0 md5
# IPv6 local connections:
host all all ::1/128 md5
host all all ::0/0 md5
# Allow replication connections from localhost, by a user with the
# replication privilege.
local replication all trust
host replication all 127.0.0.1/32 md5
host replication all ::1/128 md5
##############################################################" > /var/lib/pgsql/12/data/pg_hba.conf

—

Shell

# update runtime variable "listen_addresses"
echo "listen_addresses='*' " >> /var/lib/pgsql/12/data/postgresql.auto.conf

—

Shell

# as root: server start
systemctl start postgresql-12

2: Setup PgBouncer

Shell

# Install the postgres community package connection pooler

yum install -y pgbouncer

# Configure pgbouncer for non-SSL access

mv /etc/pgbouncer/pgbouncer.ini /etc/pgbouncer/pgbouncer.ini_backup

There’s not much to this first iteration configuring pgbouncer. All that is required is to validate that a connection can be made before updating the SSL configuration.

Shell

# edit pgbouncer.ini

echo "

[databases]

* = host=localhost

[pgbouncer]

logfile = /var/log/pgbouncer/pgbouncer.log

pidfile = var/run/pgbouncer/pgbouncer.pid

listen_addr = *

listen_port = 6432

;;any, trust, plain, md5, cert, hba, pam

auth_type = plain

auth_file = /etc/pgbouncer/userlist.txt<br />admin_users = postgres

" > /etc/pgbouncer/pgbouncer.ini

NOTE: best practice recommends hashing the passwords when editing the file userlist.txt,. But for our purposes, keeping things simple, we’ll leave the passwords in the clear.

Shell

# edit userlist.txt

echo "

\"usr1\" \"usr1\"

\"postgres\" \"postgres\"

" > /etc/pgbouncer/userlist.txt

Shell

# as root: server start

systemctl start pgbouncer

Shell

# test connectivity to the postgres server

psql 'host=localhost dbname=postgres user=postgres password=postgres' -c 'select now()'

psql 'host=localhost dbname=postgres user=usr1 password=usr1' -c 'select now()'

# test connectivity to pgbouncer

psql 'host=localhost dbname=postgres user=postgres password=postgres port=6432' -c 'select now()'

psql 'host=localhost dbname=postgres user=usr1 password=usr1 port=6432' -c 'select now()'

Step 3: Setup SSL/TSL Certificates

Create a root certificate fit for signing certificate requests:

Shell

#!/bin/bash

set -e

#################

HOST='blog'

ROOT='root'

OPENSSL_CNF='/etc/pki/tls/openssl.cnf'

#################

# GENERATE CERTIFICATE REQUEST

openssl req -new -nodes -text -out $ROOT.pem -keyout $ROOT.key -subj "/CN=$ROOT.$HOST"

# SIGN THE REQUEST WITH THE KEY TO CREATE A ROOT CERTIFICATE AUTHORITY

openssl x509 -req -in $ROOT.pem -text -days 3650 -extfile $OPENSSL_CNF -extensions v3_ca -signkey $ROOT.key -out $ROOT.crt

chmod 600 root.key

chmod 664 root.crt root.pem

Create two sets of keys and certificate requests, one for pgbouncer and postgres respectively. The certificate requests are signed with the newly created root certificate:

Shell

#!/bin/bash

# usage

# ./02.mkcert.sh <key name>

set -e

#################

HOST='blog'

SUBJ="/C=US/ST=Washington/L=Seattle/O=Percona/OU=Professional Services/CN=$HOST/[email protected]"

REQ="$1.pem"

KEY="$1.key"

CRT="$1.crt"

ROOT="root"

#################

# GENERATE PRIVATE KEY

openssl genrsa -out $KEY 2048

# GENERATE CERTIFICATE REQUEST

openssl req -new -sha256 -key $KEY -out $REQ -subj "$SUBJ"

# CERTIFICATE SIGNED BY ROOT CA

# which was generated by script "mkcert_root.sh"

openssl x509 -req -in $REQ -text -days 365 -CA $ROOT.crt -CAkey $ROOT.key -CAcreateserial -out $CRT

chmod 600 $KEY

chmod 664 $REQ

chmod 664 $CRT

Validate the signed certificates:

Shell

#!/bin/bash

set -e

# check: private key

for u in $(ls *.key)

echo -e "\n==== PRIVATE KEY: $u ====\n"

openssl rsa -in $u -check

# check: certificate request

for u in $(ls *.pem)

echo -e "\n==== CERTIFICATE REQUEST: $u ====\n"

openssl req -text -noout -verify -in $u

# check: signed certificate

for u in $(ls *.crt)

echo -e "\n==== SIGNED CERTIFICATE: $u ====\n"

openssl req -text -noout -verify -in $u

Step 4: Install Certificates and Configure Servers For SSL Connectivity

Update ownership for keys and certificates:

Shell

#!/bin/bash

set -e

chown pgbouncer:pgbouncer pgbouncer.*

chown postgres:postgres server.*

Move keys and certificates into their respective locations:

Shell

#!/bin/bash

set -e

# pgbouncer

mv pgbouncer.* /etc/pgbouncer

cp root.crt /etc/pgbouncer

# postgres

mv server.* /var/lib/pgsql/13/data

cp root.crt /var/lib/pgsql/13/data

Update pgbouncer.ini:

Shell

echo "

;;; TLS settings for connecting to backend databases

;server_tls_sslmode = prefer | require | verify-ca | verify-full

server_tls_sslmode = require

server_tls_ca_file = /etc/pgbouncer/root.crt

server_tls_key_file = /etc/pgbouncer/pgbouncer.key

server_tls_cert_file = /etc/pgbouncer/pgbouncer.crt

;;; TLS settings for accepting client connections

;client_tls_sslmode = prefer | require | verify-ca | verify-full

client_tls_sslmode = require

client_tls_ca_file = /etc/pgbouncer/root.crt

client_tls_key_file = /etc/pgbouncer/pgbouncer.key

client_tls_cert_file = /etc/pgbouncer/pgbouncer.crt

" >> /etc/pgbouncer/pgbouncer.ini

Update postgresql.auto.conf:

Shell

echo "

ssl = 'on'

ssl_ca_file = 'root.crt'

" >> /var/lib/pgsql/12/data/postgresql.auto.conf

Shell

# update runtime parameters by restarting the postgres server

systemctl restart postgresql-13

# restarting connection pooler

systemctl restart pgbouncer

And validate SSL connectivity:

Shell

#<br /># validate ssl connectivity, note the use of "sslmode"

# connect to pgbouncer

psql 'host=blog dbname=postgres user=postgres password=postgres port=6432 sslmode=require'<<<"select 'hello world' as greetings"

greetings

-------------

hello world

# connect to postgres server

psql 'host=blog dbname=postgres user=usr1 password=usr1 port=5432 sslmode=require' \

<<<"select datname,usename, ssl, client_addr

from pg_stat_ssl

join pg_stat_activity

on pg_stat_ssl.pid = pg_stat_activity.pid

where datname is not null

and usename is not null

order by 2;"

Shell

/* ATTENTION:

-- host name resolution is via IPv6

-- 1st row is a server connection from pgbouncer established by the previous query

-- 2nd row is connection generating the results of this query

datname | usename | ssl | client_addr

---------+----------+-----+--------------------------

postgres | postgres | t | ::1

postgres | postgres | t | fe80::216:3eff:fec4:7769

CAVEAT: A Few Words About Those Certificates

Using certificates signed by a Certificate Authority offers one the ability to yet go even further than simply enabling SSL sessions. For example, although not covered here, you can dispense using passwords and instead rely on the certificate’s identity as the main authentication mechanism.

Remember: you can still conduct SSL sessions via the use of self-signed certificates, it’s just that you can’t leverage the other cool validation methods in postgres.

# #######################################################
# PGBOUNCER.INI
# Only try an SSL connection. If a root CA file is present,
# verify the certificate in the same way as if verify-ca was specified
#
client_tls_sslmode = require
server_tls_sslmode = require
#
# Only try an SSL connection, and verify that the server certificate
# is issued by a trusted certificate authority (CA)
#
client_tls_sslmode = verify-ca
server_tls_sslmode = verify-ca
#
# Only try an SSL connection, verify that the server certificate
# is issued by a trusted CA and
# that the requested server host name
# matches that in the certificate
#
client_tls_sslmode = verify-full

And finally; don’t forget to save the root certificate’s private key, root.key, in a safe place!

Step 1: Setup Postgres

2: Setup PgBouncer

Step 3: Setup SSL/TSL Certificates

Step 4: Install Certificates and Configure Servers For SSL Connectivity

CAVEAT: A Few Words About Those Certificates

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