/etc/strongswan.conf

The /etc/strongswan.conf file is the main configuration file for the strongSwan IPsec VPN suite. strongSwan is an open-source, cross-platform IPsec-based VPN solution that provides secure communications. The strongswan.conf file is used to configure global strongSwan settings, logging, and various other parameters.

Purpose

The strongswan.conf file is used to configure various aspects of the strongSwan daemon, including logging levels, plugins, and other global settings. This file complements the more specific connection configurations typically found in /etc/ipsec.conf.

Structure of strongswan.conf

The configuration file uses a hierarchical structure, typically defined in sections and subsections. Each section can contain various options and values.

Example strongswan.conf

Here is a basic example of what a typical strongswan.conf might look like:

# /etc/strongswan.conf - strongSwan configuration file

# Global configuration section
charon {
    # Number of worker threads in charon
    threads = 16

    # Debug level control
    filelog {
        /var/log/charon.log {
            time_format = %b %e %T
            append = no
            default = 1
            flush_line = yes
        }
    }

    syslog {
        identifier = charon
        daemon {
            ike = 2
            cfg = 2
            knl = 2
            net = 2
        }
        auth {
            peer = 2
        }
    }

    # Plugins to load
    plugins {
        include strongswan.d/charon/*.conf
    }
}

# Configuration for the 'starter' daemon
starter {
    load_warning = no
    auto_pkcs11 = yes
}

Sections and Options

1. Global Configuration (charon):

   • threads: Number of worker threads to handle IKE (Internet Key Exchange) operations.

   • filelog: Specifies logging to a file.

     • time_format: Format of the timestamp.

     • append: Whether to append to the log file or overwrite it.

     • default: Default log level.

     • flush_line: Whether to flush the log file after each line.

   • syslog: Configures logging to the system logger.

     • identifier: Identifier for syslog messages.

     • daemon: Log levels for various subsystems (ike, cfg, knl, net).

     • auth: Log levels for authentication messages (peer).

2. Plugins:

   • include: Includes additional plugin configuration files from a specified directory.

3. Starter Configuration (starter):

   • load_warning: Controls whether warnings are displayed for load operations.

   • auto_pkcs11: Automatically loads PKCS#11 modules.

Configuration Options

• Logging: Adjusting log levels for different components can help with debugging and monitoring.

• Threads: Configuring the number of threads can optimize performance based on the system's capabilities.

• Plugins: Enable or disable specific plugins as needed, depending on the features and functionalities required.

Using strongswan.conf

After editing the strongswan.conf file, it's essential to restart the strongSwan service to apply the changes. This can be done using systemd on most modern Linux distributions:

sudo systemctl restart strongswan

Conclusion

The /etc/strongswan.conf file is a critical component in configuring and managing a strongSwan IPsec VPN. By properly setting global options, logging levels, and plugin configurations, administrators can tailor the strongSwan environment to meet their specific needs, ensuring efficient and secure VPN operations. Always ensure to back up the configuration file before making significant changes and thoroughly test the configuration in a staging environment if possible.