问题：

在多节点环境上运行MPI程序，出现错误：

HYDU_sock_connect (utils/sock/sock.c:145): unable to connect from "2" to "1" (No route to host) main (pm/pmiserv/pmip.c:183): unable to connect to server digital4.ocean at port 42355 (check for firewalls!) HYDU_sock_connect (utils/sock/sock.c:145): unable to connect from "3" to "1" (No route to host) main (pm/pmiserv/pmip.c:183): unable to connect to server digital4.ocean at port 42355 (check for firewalls!)

解决：

1、关闭防火墙

关闭防火墙，即可运行成功

systemctl stop firewalld

2、修改hosts文件

可能是客户端连接不到服务器引起的，在客户端的host文件中添加相关的ip和主机名，如node2中：

10.10.1.12 node1 10.10.1.56 node3

3、防火墙添加富规则

在node1（服务端）的防火墙中添加富规则：

firewall-cmd --add-rich-rule='rule family="ipv4" source address="(node2的ip)" accept' firewall-cmd --add-rich-rule='rule family="ipv4" source address="(node3的ip)" accept'

查看添加的富规则：

firewall-cmd --list-rich-rules

移除添加的富规则：

firewall-cmd --remove-rich-rule='rule family="ipv4" source address="(node2的ip)" accept' firewall-cmd --remove-rich-rule='rule family="ipv4" source address="(node3的ip)" accept'