Configuring rlogin remsh rcp to not request login password

Abstract

The main purpose of this article is to clarify that [r]commands (remsh, rlogin, rcp) requires either the source FQDN or it's an alias on the same domain of the destiny server on the /etc/hosts file of the destiny server. How the source clients resolve the destiny (IP, FQDN, alias) of themself or the target server is of no consecuence.

The Operating Environment (11.11, 11.23 or 11.31) plays no different in the problem. If you found that this behaivor is consistent across the systems, review steps by step to determina how hostname resolution is performed on the server, that is frequently the source of all issues with remsh.

NOTE: Multiple FQDN entries in /etc/hosts file of the same IP Address are not supported because alias to FQDN translation may not occur correctly.

Test Enviroment

The three servers are configure to resolve host using /etc/hosts file.

FQDN                   alias   OS.Rev. IP Address      Function
===============================================================
cobble.alf.cpqcorp.net cobble  11.11   16.113.011.181  Target
jets.rose.hp.com       jets    11.11   15.043.235.193  Source
delta.cri.hp.com       delta   11.31   16.090.048.075  Source

Using the correct FQDN

-> /etc/hosts
127.0.0.1       localhost       loopback
16.113.11.181   cobble.alf.cpqcorp.net cobble
15.43.235.193   jets.rose.hp.com        jets
16.90.48.75     delta.cri.hp.com delta
#15.43.235.193   jets.alf.cpqcorp.net    jets
#16.90.48.75     delta.alf.cpqcorp.net delta

-> $HOME/.rhosts
delta.cri.hp.com        root
jets.rose.hp.com        root
#jets    root
#delta   root

delta: / # rlogin cobble
jets: / # rlogin cobble

This configuration works correctly. Neither rlogin or remsh request use password from jets and delta. The source client is resolve to the FQDN on cobble /etc/hosts file.

cobble: / # who -R
root       pts/0        Aug  4 13:11  (jets.rose.hp.com)
root       pts/1        Aug  4 13:12  (delta.cri.hp.com)

Using alias without changing FQDN entries

-> /etc/hosts
127.0.0.1       localhost       loopback
16.113.11.181   cobble.alf.cpqcorp.net cobble
15.43.235.193   jets.rose.hp.com        jets
16.90.48.75     delta.cri.hp.com delta
#15.43.235.193   jets.alf.cpqcorp.net    jets
#16.90.48.75     delta.alf.cpqcorp.net delta

-> $HOME/.rhosts
#delta.cri.hp.com        root
#jets.rose.hp.com        root
jets    root
delta   root

delta: / # rlogin cobble
jets: / # rlogin cobble

This configuration doesn't work correctly. Either rlogin and remsh request request password from jets and delta. The source client is resolve to their correct FQDN (rose.hp.com & cri.hp.com) on cobble /etc/host file.

cobble: / # who -R
root       pts/0        Aug  4 13:29  (jets.rose.hp.com)
root       pts/1        Aug  4 13:29  (delta.cri.hp.com)

Using alias changing FQDN entries

-> /etc/hosts
127.0.0.1       localhost       loopback
16.113.11.181   cobble.alf.cpqcorp.net cobble
#15.43.235.193   jets.rose.hp.com        jets
#16.90.48.75     delta.cri.hp.com delta
15.43.235.193   jets.alf.cpqcorp.net    jets
16.90.48.75     delta.alf.cpqcorp.net delta

-> $HOME/.rhosts
#delta.cri.hp.com        root
#jets.rose.hp.com        root
jets    root
delta   root

delta: / # rlogin cobble
jets: / # rlogin cobble

This configuration works correctly. Neither rlogin or remsh request password from jets and delta. The source client hostname is resolved to the "false" FQDN (alf.cpqcorp.net) on cobble /etc/host file.

cobble: / # who -R
root       pts/0        Aug  4 13:36  (jets.alf.cpqcorp.net)
root       pts/1        Aug  4 13:36  (delta.alf.cpqcorp.net)

Authors

• Alejandro Marin Badilla