For the Perforce service (server, broker, or proxy), the port number on which it listens, and the network transport(s) to which it is to bind.

For Perforce applications, the protocol, host and port number of the Perforce service with which to communicate. The most commonly-used communications protocols are tcp (plaintext over TCP/IP) or ssl (SSL over TCP/IP).

Perforce supports connectivity over IPv6 networks as well as over IPv4 networks. You can specify whether you require (or merely prefer) to use IPv4 or IPv6 addresses when resolving hostnames. The protocol settings of tcp4 and ssl4 require IPv4 address support. Similarly, tcp6 and ssl6 require IPv6 support. Using tcp64 and ssl64 attempts first to resolve the host to an IPv6 address, but will accept an IPv4 address if IPv6 is not available. The opposite behavior is available with tcp46 and ssl46; these default to the use of IPv4 if possible, and use IPv6 if IPv4 is unavailable. A configurable, net.rfc3484, may be set on user workstations or in P4CONFIG files in order to permit the operating system to automatically determine which transport to use.

Behavior and performance of networked services is contingent not merely upon the networking capabilities of the machine that hosts the service, nor only on the operating systems used by the end users, but also on your specific LAN and WAN infrastructure (and the state of IPv6 support for every router between the end user and the Perforce versioning service).

To illustrate just one possible scenario, a user working from home; even if they have an IPv6-based home network, their ISP or VPN provider may not fully support IPv6. We have consequently provided several variations on P4PORT to provide maximum flexibility and backwards compatibility for administrators and users during the transition from IPv4 to IPv6.

In mixed environments it is good practice to set the net.rfc3484 configurable to 1:

p4 configure set net.rfc3484=1

Doing so ensures RFC3484-compliant behavior for users who do not explicitly specify the protocol value; that is, if the client-side configurable net.rfc3484 is set to 1, and P4PORT is set to example.com:1666, or tcp:example.com:1666, or ssl:example.com:1666, the user's operating system will automatically determine, for any given connection, whether to use IPv4 or IPv6.

If you use SSL to connect to Perforce, the fingerprint of the Perforce server must match that stored in the P4TRUST file. (When you connect to a new Perforce installation for the first time, the server's fingerprint is displayed. If it matches the one your administrator has assigned it, you may safely connect to the server by using the p4 trust command to add the server to your P4TRUST file.)

The format of P4PORT for Perforce applications is protocol:host:port, or port by itself if both the Perforce application and versioning service are running on the same host. Port numbers must be in the range 1024 through 32767.

If you specify both an IP address and a port number in P4PORT, the Perforce versioning service ignores requests from any IP addresses other than the one specified in P4PORT.

If you do not specify a protocol, transmissions between Perforce applications and the Perforce versioning service are performed in plaintext, and IPv4 addresses are assumed.