Module java.base

Class SocketPermission

All Implemented Interfaces:
Serializable, Guard

public final class SocketPermission extends Permission implements Serializable
This class represents access to a network via sockets. A SocketPermission consists of a host specification and a set of "actions" specifying ways to connect to that host. The host is specified as
    host = (hostname | IPv4address | iPv6reference) [:portrange]
    portrange = portnumber | -portnumber | portnumber-[portnumber]
The host is expressed as a DNS name, as a numerical IP address, or as "localhost" (for the local machine). The wildcard "*" may be included once in a DNS name host specification. If it is included, it must be in the leftmost position, as in "*".

The format of the IPv6reference should follow that specified in RFC 2732: Format for Literal IPv6 Addresses in URLs:

    ipv6reference = "[" IPv6address "]"
For example, you can construct a SocketPermission instance as the following:
    String hostAddress = inetaddress.getHostAddress();
    if (inetaddress instanceof Inet6Address) {
        sp = new SocketPermission("[" + hostAddress + "]:" + port, action);
    } else {
        sp = new SocketPermission(hostAddress + ":" + port, action);
    String host = url.getHost();
    sp = new SocketPermission(host + ":" + port, action);

The full uncompressed form of an IPv6 literal address is also valid.

The port or portrange is optional. A port specification of the form "N-", where N is a port number, signifies all ports numbered N and above, while a specification of the form "-N" indicates all ports numbered N and below. The special port value 0 refers to the entire ephemeral port range. This is a fixed range of ports a system may use to allocate dynamic ports from. The actual range may be system dependent.

The possible ways to connect to the host are

The "listen" action is only meaningful when used with "localhost" and means the ability to bind to a specified port. The "resolve" action is implied when any of the other actions are present. The action "resolve" refers to host/ip name service lookups.

The actions string is converted to lowercase before processing.

As an example of the creation and meaning of SocketPermissions, note that if the following permission:

   p1 = new SocketPermission("", "connect,accept");
is granted to some code, it allows that code to connect to port 7777 on, and to accept connections on that port.

Similarly, if the following permission:

   p2 = new SocketPermission("localhost:1024-", "accept,connect,listen");
is granted to some code, it allows that code to accept connections on, connect to, or listen on any port between 1024 and 65535 on the local host.

Note: Granting code permission to accept or make connections to remote hosts may be dangerous because malevolent code can then more easily transfer and share confidential data among parties who may not otherwise have access to the data.

External Specifications
See Also: