---
name: "v4rcp"
section: "1"
platform: "linux"
package: "krb5-clients"
version: "1.6.dfsg.4~beta1-5lenny7"
release: "Debian 5.0 (Lenny)"
platforms: ["linux"]
url: "https://new.carta.tech/v4rcp"
---

# v4rcp(1)

back end for Kerberos V4 rcp

## NAME

v4rcp - back end for Kerberos V4 rcp

## SYNOPSIS

**v4rcp** *not invoked by users*

## DESCRIPTION

This program is **not** for user execution. The usage message indicates this.

Kerberos Version 4  *rsh* did not support encryption. In order to perform encrypted file transfer, the version 4 *rcp* program did a second authentication, directly to the  *rcp* process at the other end. This meant that *rcp* needed to be *setuid* to root in order to read the *krb-srvtab* file on the remote end.

Rather than add this complexity into the main Kerberos 5  *rcp* the Kerberos 5  *kshd* instead detects the use of Kerberos 4 authentication, and checks the command for the program name *rcp* and then substitutes the full pathname of *v4rcp* instead.  Since *v4rcp* is installed *setuid* to root, it can perform the the authentication and get the session key needed to encrypt the file transfer.

Kerberos 5  *rcp* instead uses the encryption support built in to Kerberos 5 *rsh* and *kshd* directly.

## SEE ALSO

[rsh(1)](/rsh/1.md), [rcp(1)](/rcp/1.md), [kshd(8)](/kshd/8.md)