ORA-17629: Cannot connect to the remote database server

rman远程连接目标库，提示报错ORA-17629: Cannot connect to the remote database server，首先排查网络问题是否通路，结果发现目标端防火墙是开着的，linux7永久关闭防火墙

contents of Memory Script:
{
backup as copy reuse
targetfile '/u1/db/oracle/product/11.2.0/db_1/dbs/orapworcl1' auxiliary format
'/u1/db/oracle/product/11.2.0/db_1/dbs/orapworcl_stb' ;
}
executing Memory Script

Starting backup at 19-AUG-21
released channel: p1
released channel: p2
released channel: s1
released channel: s2
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 08/19/2021 16:27:06
RMAN-05501: aborting duplication of target database
RMAN-03015: error occurred in stored script Memory Script
RMAN-03009: failure of backup command on p1 channel at 08/19/2021 16:27:06
ORA-17629: Cannot connect to the remote database server
ORA-17627: ORA-12543: TNS:destination host unreachable
ORA-17629: Cannot connect to the remote database server

关闭目标端防火墙

[root@rac-dg ~]# systemctl stop firewalld
[root@rac-dg ~]#
[root@rac-dg ~]#
[root@rac-dg ~]# systemctl disable firewalld
Removed symlink /etc/systemd/system/multi-user.target.wants/firewalld.service.
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.

[oracle@rac2 admin]$ ping 192.168.163.27
PING 192.168.163.27 (192.168.163.27) 56(84) bytes of data.
64 bytes from 192.168.163.27: icmp_seq=1 ttl=64 time=0.246 ms
^C
--- 192.168.163.27 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.246/0.246/0.246/0.000 ms
[oracle@rac2 admin]$
[oracle@rac2 admin]$ rman target sys/oracle@orcl1 auxiliary sys/oracle@orcl_stb

Recovery Manager: Release 11.2.0.4.0 - Production on Thu Aug 19 16:29:56 2021

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

connected to target database: ORCL (DBID=1608598914)
connected to auxiliary database: ORCL (not mounted)

RMAN>

Recovery Manager complete.