Labeled IPsec with LibreSwan

Introduction

Libreswan is an open-source implementation of the Internet Protocol Security (IPsec) protocol. IPsec is a widely used technology for securing communication over the internet. Labeled IPsec is an extension of IPsec that provides mandatory access control (MAC) to IPsec packets based on the security labels. In this article, we will discuss how labeled IPsec can be implemented with Libreswan.

Implement labeled IPsec

To implement labeled IPsec with Libreswan, we need to use the Security Enhanced Linux (SELinux) policy. SELinux provides a mechanism for labeling the network traffic based on security policies. The labeled IPsec implementation requires the SELinux policy to label the IPsec packets based on the security context of the process that creates them.

The first step in implementing labeled IPsec with Libreswan is to ensure that SELinux is enabled and running on the system. We also need to ensure that the SELinux policy for IPsec is installed on the system. This policy can be installed using the package manager of the distribution. For example, on a Red Hat-based distribution, we can install the policy using the command:

yum install setroubleshoot-server selinux-policy-targeted

Once SELinux and the IPsec policy are installed, we need to configure the Libreswan to use the labeled IPsec. We can do this by adding the label=yes option in the ipsec.conf file. The ipsec.conf file is the main configuration file for Libreswan. We can add the following lines in the ipsec.conf file:

config setup
    protostack=netkey
    nat_traversal=yes

conn labeled-conn
    left=192.168.1.100
    leftsubnet=192.168.1.0/24
    leftid=@server
    right=%any
    rightsubnet=10.0.0.0/24
    rightid=@client
    authby=secret
    pfs=no
    auto=add
    label=yes

In the above configuration, we have added the label=yes option to the labeled-conn connection. This will enable the labeled IPsec for this connection. We have also specified the left and right IP addresses, subnets, and identities for the connection.

After configuring the ipsec.conf file, we need to modify the SELinux policy to allow the labeled IPsec traffic. We can modify the SELinux policy using the semanage command. The semanage command is used to manage the SELinux policy on the system. We can add the following rule in the SELinux policy using the semanage command:

semanage port -a -t ipsec_policy_port_t -p esp
The above command adds a new rule in the SELinux policy to allow the esp protocol on the ipsec_policy_port_t port.

Once the SELinux policy is modified, we can start the Libreswan service and establish the labeled IPsec connection. We can use the following commands to start the Libreswan service:

systemctl start ipsec
systemctl enable ipsec

After starting the Libreswan service, we can establish the labeled IPsec connection using the ipsec auto –up labeled-conn command.

Conclusion

In conclusion, labeled IPsec can be implemented with Libreswan by enabling SELinux, installing the SELinux policy for IPsec, configuring the ipsec.conf file, modifying the SELinux policy to allow labeled IPsec traffic, and starting the Libreswan service. Labeled IPsec provides mandatory access control for IPsec packets based on security labels, which enhances the security.