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P4 Server Administration Documentation | 2026.1

# Reject client connection requests

By default, all P4 client applications can access the server. You can block one or more client programs from accessing the P4 Server by setting the `rejectList` configurable. Changes to this configurable take effect immediately. No server restart is required.

The syntax for setting `rejectList`:

    rejectList=programName[[,programName]...]

The syntax of `programName`:

    programName[,version=versionName]

No wildcard character is allowed in the programName.

To block requests from all P4EXP plugins, regardless of the version:

    $ p4 configure set rejectList=P4EXP

The log does not include information about the rejected connection attempt.

## Block specific versions

To block requests from versions you specify, use the default separator, which is the comma (,):

    $ p4 configure set rejectList=p4,version=13.1,p4,version=13.2

Use quotation marks to enclose the expression after the `=` sign if the expression contains any blank spaces:

    $ p4 configure set rejectList="p4,version=13.1, p4,version=13.2"

## Block build number and platform

You can block a program version using a build number:

    $ p4 configure set rejectList=p4,version=1221235

You can block a program by platform:

    $ p4 configure set rejectList=p4,version=DARWIN90X86_64

You can block by build number and platform:

    $ p4 configure set rejectList=p4,version=1221235,p4,version=DARWIN90X86_64

You can block more than one program:

    $ p4 configure set rejectList=P4EXP,p4,version=1221235,p4,version=DARWIN90X86_64

## Unset the configurable

To unset the configurable, use

`p4 configure unset rejectList`

If you accidentally blocked the `p4` client application, you can still unset the configurable by using this `p4d` command:

    $ p4d -r P4ROOT "-cunset rejectList"

where `P4ROOT` represents the literal value of P4ROOT. (See `-r` and `-cunset server#var` in P4 Server (p4d) reference.)

## Block P4V clients from accessing P4 Server

P4V passes its version information in the `program` string, not in a `version` string. For example, if you want to block P4V clients version 2021.2 and 2022.1 on Windows as well as version 2021.2 on Linux:

    $ p4 configure set rejectList=P4V/NTX64/2021.2,P4V/NTX86/2022.1,P4V/LINUX26X86_64/2021.2

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