友情提醒：rsh的安全性是没有保证的，所有密码均使用明文传输，如果服务器有大量对外服务，建议不要使用此协议
转载自：
<a href="http://os.51cto.com/art/201004/192308.htm">http://os.51cto.com/art/201004/192308.htm</a>
<a href="http://liangqi1188.blog.163.com/blog/static/39916047200909111512741/">http://liangqi1188.blog.163.com/blog/static/39916047200909111512741/</a>
我们在使用CentOS系统时候，安装RAC时，需要配置各个节点的互信关系，使rsh、rlogin、rcp等命令不需要输入密码可以操作其他节点。
除了按照管法rac安装文档中的方法配置ssh之外，还可以通过修改.rhosts等文件实现互信。在unix（如aix）中，
可以简单修改/etc/hosts.equiv实现，但是Linux中比较麻烦，需要一些其他的步骤，下面我们来演示在CentOS系统中配置方法：
一、CentOS系统时需要在各个节点上完成如下操作
1、检查在CentOS系统中rsh-server包是否已经安装 [root@rac1 ~]# rpm -qa|grep -i ^rsh-server
rsh-server-0.17-40.el5 如果没有安装使用rpm -ivh 命令安装
2、确保/etc/xinetd.d/rlogin中存在disable = no这一行
[root@rac1 ~]# cat /etc/xinetd.d/rlogin
# default: on
# description: rlogind is the server for the rlogin(1) program. The server
# provides a remote login facility with authentication based on
# privileged port numbers from trusted hosts. service login
{disable = no
socket_type = stream
wait = no
user = root
log_on_success += USERID
log_on_failure += USERID
server = /usr/sbin/in.rlogind}
3、确保/etc/xinetd.d/rsh中存在disable = no这一行
[root@rac1 ~]# cat /etc/xinetd.d/rsh
# default: on
# description: The rshd server is the server for the rcmd(3) routine and,
# consequently, for the rsh(1) program. The server provides
# remote execution facilities with authentication based on
# privileged port numbers from trusted hosts. service shell
{disable = no
socket_type = stream
wait = no
user = root
log_on_success += USERID
log_on_failure += USERID
server = /usr/sbin/in.rshd}
4、在CentOS系统重启xinetd服务
[root@rac1 ~]# service xinetd restart
Stopping xinetd: [ OK ]
Starting xinetd: [ OK ]
5、在CentOS系统编辑/etc/securetty，确保存在rexec、rsh、rlogin三行
[root@rac1 ~]# cat /etc/securetty
console
vc/1
vc/2
vc/3
vc/4
vc/5
vc/6
vc/7
vc/8
vc/9
vc/10
vc/11
tty1
tty2
tty3
tty4
tty5
tty6
tty7
tty8
tty9
tty10
tty11
rexec
rsh
rlogin
6、在CentOS系统编辑/etc/hosts.equiv文件，如下所示
[root@rac1 ~]# cat /etc/hosts.equiv
+rac1 oracle
+rac2 oracle
+rac1-priv oracle
+rac2-priv oracle
+rac1 root
+rac2 root
+rac1-priv root
+rac2-priv root
7、在CentOS系统编辑/etc/hosts文件，如下所示 [root@rac1 ~]# cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost ::1 localhost6.localdomain6 localhost6
#public 192.168.2.101 rac1.localdomain rac1 192.168.2.102 rac2.localdomain rac2
#private 192.168.0.101 rac1-priv.localdomain rac1-priv 192.168.0.102 rac2-priv.localdomain rac2-priv
#virtual 192.168.2.111 rac1-vip.localdomain rac1-vip 192.168.2.112 rac2-vip.localdomain rac2-vip
8、在CentOS系统编辑~/.rhosts，如下所示 [root@rac1 ~]# cat ~/.rhosts
rac1 root
rac2 root
rac1-priv root
rac2-priv root
9、测试rlogin和rsh是否可以不用输入密码登录其他节点
[root@rac1 ~]# rlogin rac2
connect to address 192.168.2.102 port 543: Connection refused
Trying krb4 rlogin...
connect to address 192.168.2.102 port 543: Connection refused
trying normal rlogin (/usr/bin/rlogin)
Last login: Wed Jan 13 08:39:17 from rac1
[root@rac2 ~]# hostname rac2.localdomain
[root@rac2 ~]# exit
logout rlogin: connection closed.
[root@rac1 ~]# rsh rac2
connect to address 192.168.2.102 port 543: Connection refused
Trying krb4 rlogin... connect to address 192.168.2.102 port 543: Connection refused
trying normal rlogin (/usr/bin/rlogin)
Last login: Wed Jan 13 08:47:22 from rac1
[root@rac2 ~]# hostname rac2.localdomain
[root@rac2 ~]# exit
logout rlogin: connection closed.
这样，我们就完成了在CentOS系统配置rsh,rcp,scp多节点互通，而且不需要密码。
二、相关排错
在多机集成环境中，Server将根据环境的配置与域内的Client协同工作，但是有些时候会出现一些让人摸不着头脑的错误。解决步骤如下：
1、注意，时候虽然进行了上述的配置，但是从客户端上进行连接的时候，仍然出现"No route to host"的错误？
解决方法：关闭防火墙。
2、在集群的所有节点都已经配置好了.rhosts和/etc/hosts的信息，并且rsh服务已经打开，防火墙已经关闭。rsh hostname已经通过测试，但是使用rsh hostname “rcmd” 来执行命令，未能通过。出现no route to host错误。
解决方法：关闭selinux。转载于:https://my.oschina.net/766/blog/210975