The stunnel package contains a program that allows you to encrypt arbitrary TCP connections inside SSL (Secure Sockets Layer) so you can easily communicate with clients over secure channels. stunnel can also be used to tunnel PPP over network sockets without changes to the server package source code.
![[Note]](../images/note.png)
Development versions of BLFS may not build or run some packages properly if LFS or dependencies have been updated since the most recent stable versions of the books.
Download (HTTP): https://www.stunnel.org/downloads/archive/5.x/stunnel-5.76.tar.gz
Download MD5 sum: cea53ba1a7c7bcb3359da2951ab32999
Download size: 908 KB
Estimated disk space required: 7.4 MB
Estimated build time: less than 0.1 SBU
libnsl-2.0.1, netcat (required for tests), tcpwrappers, and TOR
The stunnel daemon
will be run in a chroot jail by an unprivileged
user. Create the new user and group using the following commands as
the root user:
groupadd -g 51 stunnel &&
useradd -c "stunnel Daemon" -d /var/lib/stunnel \
-g stunnel -s /bin/false -u 51 stunnel
A signed SSL Certificate and a Private Key is necessary to run
the stunnel daemon.
After the package is installed, there are instructions to
generate them. However, if you own or have already created a
signed SSL Certificate you wish to use, copy it to /etc/stunnel/stunnel.pem before starting the
build (ensure only root has read
and write access). The .pem file
must be formatted as shown below:
-----BEGIN PRIVATE KEY-----
<many encrypted lines of private key>
-----END PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
<many encrypted lines of certificate>
-----END CERTIFICATE-----
-----BEGIN DH PARAMETERS-----
<encrypted lines of dh parms>
-----END DH PARAMETERS-----Install stunnel by running the following commands:
./configure --prefix=/usr \
--sysconfdir=/etc \
--localstatedir=/var \
--disable-systemd &&
make
If you have installed the optional netcat application, the regression tests can be run with make check.
Now, as the root user:
make docdir=/usr/share/doc/stunnel-5.76 install
If you do not already have a signed SSL Certificate and Private
Key, create the stunnel.pem file in
the /etc/stunnel directory using the
command below. You will be prompted to enter the necessary
information. Ensure you reply to the
Common Name (FQDN of your server) [localhost]:prompt with the name or IP address you will be using to access the service(s).
To generate a certificate, as the root user, issue:
make cert
--disable-systemd: This
switch disables systemd socket activation support which is not
available in BLFS.
make docdir=... install: This command installs the package and changes the documentation installation directory to standard naming conventions.
As the root user, create the
directory used for the .pid file
created when the stunnel daemon
starts:
install -v -m750 -o stunnel -g stunnel -d /var/lib/stunnel/run && chown stunnel:stunnel /var/lib/stunnel
Next, create a basic /etc/stunnel/stunnel.conf configuration file
using the following commands as the root user:
cat > /etc/stunnel/stunnel.conf << "EOF"
; File: /etc/stunnel/stunnel.conf
; Note: The pid and output locations are relative to the chroot location.
pid = /run/stunnel.pid
chroot = /var/lib/stunnel
client = no
setuid = stunnel
setgid = stunnel
cert = /etc/stunnel/stunnel.pem
;debug = 7
;output = stunnel.log
;[https]
;accept = 443
;connect = 80
;; "TIMEOUTclose = 0" is a workaround for a design flaw in Microsoft SSL
;; Microsoft implementations do not use SSL close-notify alert and thus
;; they are vulnerable to truncation attacks
;TIMEOUTclose = 0
EOF
Finally, add the service(s) you wish to encrypt to the configuration file. The format is as follows:
[<service>]
accept = <hostname:portnumber>
connect = <hostname:portnumber>For a full explanation of the commands and syntax used in the configuration file, issue man stunnel.
To automatically start the stunnel daemon when the system
is booted, install the /etc/rc.d/init.d/stunnel bootscript from the
blfs-bootscripts-20250225 package.
make install-stunnel