=== About ===
This program is openconnect VPN server (ocserv), a server compatible with the openconnect VPN client [0]. It is believed to be compatible with the protocol used by CISCO's AnyConnect SSL VPN.
[0]. http://www.infradead.org/openconnect/
=== Build instructions ===
To build from a distributed release use:
$ ./configure && make
To build from the git repository use:
$ autoreconf -fvi $ ./configure && make
=== Installation instructions ===
Now you need to generate a certificate. E.g. $ certtool --generate-privkey > ./test-key.pem $ certtool --generate-self-signed --load-privkey test-key.pem --outfile test-cert.pem (make sure you enable encryption or signing)
To run the server on the foreground edit the doc/sample.config and then run:
=== How the VPN works ===
The openconnect VPN server is an Internet-layer VPN server. That is, it provides the client with an IP address and a list of routes that this IP may access. Since this is not a Link-layer VPN a separate subnet must be allocated for the VPN addresses.
The subnet addresses are specified by the 'ipv4-network' and 'ipv4-netmask' configuration options (and the corresponding ipv6 options). The routes that are pushed to the client are specified by the 'route' option. For each client two IPv4 addresses are assigned, its VPN address and its local image (remember this is a point-to-point connection). The image isn't known to the client (the anyconnect protocol doesn't forward it).
Note that in order to allow high-speed transfers ocserv doesn't do any packet forwarding or filtering between the networks. It is expected that the server has any required routes or firewall rules set up. You may conditionally enable firewall rules, or even enable routing rules through the client using the 'connect-script' and 'disconnect-script' scripts based on the user who connected. You can find some examples in the doc/scripts/ directory.
=== Authentication ===
Authentication in openconnect VPN server occurs in the initial TLS session. That is an HTTPS session over which the client is provided with an XML authentication page. The server is authenticated using its certificate and the client, either by its certificate, or via username and password pairs, either via PAM or a custom password file. Various combinations can be used, e.g., certificates and passwords. Since PAM supports various authentication types, two factor authentication methods are also supported. After the user is authenticated he is provided with a cookie that can be used for future connections. The lifetime of the cookie is configurable using the 'cookie-validity' option, and is renewed on every client connection.
After the user is authenticated, directly, or via the cookie, he issues an HTTP CONNECT command which results to a direct connection with the VPN. Additionally the user could connect using UDP and Datagram TLS. That connection is authenticated using session resumption and a master key provided by the server, i.e., it is not really a DTLS 1.0 compliant connection.