环境：
11.2.0.3 ADG (db11gdb11gadgdb11gcas)
在自己先前克隆后的环境互相tnsping报错。
tnsping 本机ok，tnsping其他机器均报错：
[oracle@db11g ~]$ tnsping jingyu TNS Ping Utility for Linux: Version 11.2.0.3.0 - Production on 13-MAY-2023 08:09:11 Copyright (c) 1997, 2011, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.18)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jingyu))) OK (0 msec) [oracle@db11g ~]$ tnsping jyadg TNS Ping Utility for Linux: Version 11.2.0.3.0 - Production on 13-MAY-2023 08:09:14 Copyright (c) 1997, 2011, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.19)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jyadg))) TNS-12543: TNS:destination host unreachable [oracle@db11g ~]$ tnsping jycas TNS Ping Utility for Linux: Version 11.2.0.3.0 - Production on 13-MAY-2023 08:09:17 Copyright (c) 1997, 2011, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora Used TNSNAMES adapter to resolve the alias Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.20)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jycas))) TNS-12543: TNS:destination host unreachable 1.检查防火墙和SElinux状态
第一反应就是防火墙或SELinux导致，初步检查发现：防火墙未运行，SELinux也禁用掉。
[root@db11g ~]# service iptables status Redirecting to /bin/systemctl status iptables.service Unit iptables.service could not be found. [root@db11g ~]# getenforce Permissive [root@db11g ~]# cat /etc/sysconfig/selinux # This file controls the state of SELinux on the system. # SELINUX= can take one of these three values: # enforcing - SELinux security policy is enforced. # permissive - SELinux prints warnings instead of enforcing. # disabled - No SELinux policy is loaded. SELINUX=disabled # SELINUXTYPE= can take one of three values: # targeted - Targeted processes are protected, # minimum - Modification of targeted policy. Only selected processes are protected. # mls - Multi Level Security protection. SELINUXTYPE=targeted 配置文件tnsnames.ora同步到3个环境，保持一致：
# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/tnsnames.ora # Generated by Oracle configuration tools. JINGYU = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.18)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jingyu) ) ) JYADG = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.19)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jyadg) ) ) JYCAS = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.20)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jycas) ) ) 2.确认克隆的网卡是否正常
主要怀疑克隆是否MAC地址之类做了变化，期望是不一样的MAC，实际也是，在宿主机看arp记录的和目前的都匹配：
[oracle@bogon ~]$ arp -a|grep 1.18 bogon (192.168.1.18) at 52:54:00:6f:92:54 [ether] on br0 [oracle@bogon ~]$ arp -a|grep 1.19 localhost (192.168.1.19) at 52:54:00:d0:49:1b [ether] on br0 [oracle@bogon ~]$ arp -a|grep 1.20 localhost (192.168.1.20) at 52:54:00:71:f1:9a [ether] on br0 可现在就是网络IP可以ping通，但是tnsping说啥不通：
[oracle@bogon ~]$ ping 192.168.1.18 PING 192.168.1.18 (192.168.1.18) 56(84) bytes of data. 64 bytes from 192.168.1.18: icmp_seq=1 ttl=64 time=0.525 ms 64 bytes from 192.168.1.18: icmp_seq=2 ttl=64 time=0.312 ms ^C --- 192.168.1.18 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1024ms rtt min/avg/max/mdev = 0.312/0.418/0.525/0.108 ms [oracle@bogon ~]$ tnsping 192.168.1.18 TNS Ping Utility for Linux: Version 19.0.0.0.0 - Production on 13-MAY-2023 08:39:50 Copyright (c) 1997, 2022, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/19.3.0/db_1/network/admin/sqlnet.ora Used HOSTNAME adapter to resolve the alias Attempting to contact (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.18)(PORT=1521))) TNS-12543: TNS:destination host unreachable 3.网络层面排查1521端口
以db11g环境为例说明：
[oracle@db11g ~]$ netstat -ano|grep 1521 tcp6 0 0 :::1521 :::* LISTEN off (0.00/0/0) unix 2 [ ACC ] STREAM LISTENING 26303 /var/tmp/.oracle/sEXTPROC1521 使用telnet工具定位：
[root@bogon ~]# telnet 192.168.1.18 1521 Trying 192.168.1.18... telnet: connect to address 192.168.1.18: No route to host 而正常的环境（其他可以tnsping的正常虚机）应该类似这样：
[root@bogon ~]# telnet 192.168.1.11 1521 Trying 192.168.1.11... Connected to 192.168.1.11. Escape character is '^]'. 看来的确是网络问题了。
说没有路由可达主机，直接traceroute对比看下有何区别：
# 正常的虚机： [root@bogon ~]# traceroute 192.168.1.11 traceroute to 192.168.1.11 (192.168.1.11), 30 hops max, 60 byte packets 1 bogon (192.168.1.11) 0.556 ms 0.507 ms 0.486 ms # 不正常的虚机： [root@bogon ~]# traceroute 192.168.1.18 traceroute to 192.168.1.18 (192.168.1.18), 30 hops max, 60 byte packets 1 bogon (192.168.1.18) 0.516 ms !X 0.450 ms !X 0.404 ms !X [root@bogon ~]# traceroute 192.168.1.19 traceroute to 192.168.1.19 (192.168.1.19), 30 hops max, 60 byte packets 1 bogon (192.168.1.19) 0.546 ms !X 0.491 ms !X 0.455 ms !X [root@bogon ~]# traceroute 192.168.1.20 traceroute to 192.168.1.20 (192.168.1.20), 30 hops max, 60 byte packets 1 localhost (192.168.1.20) 0.730 ms !X 0.680 ms !X 0.648 ms !X 又回到防火墙。。之前检查命令搞错了，来吧，赶紧正常关闭防火墙：
[root@db11g ~]# systemctl status firewalld ● firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled) Active: active (running) since Sat 2023-05-13 08:38:13 CST; 23min ago Docs: man:firewalld(1) Main PID: 850 (firewalld) CGroup: /system.slice/firewalld.service └─850 /usr/bin/python2 -Es /usr/sbin/firewalld --nofork --nopid May 13 08:38:12 db11g systemd[1]: Starting firewalld - dynamic firewall dae..... May 13 08:38:13 db11g systemd[1]: Started firewalld - dynamic firewall daemon. May 13 08:38:13 db11g firewalld[850]: WARNING: AllowZoneDrifting is enabled...w. Hint: Some lines were ellipsized, use -l to show in full. [root@db11g ~]# systemctl stop firewalld 一切恢复正常：
[root@bogon ~]# traceroute 192.168.1.18 traceroute to 192.168.1.18 (192.168.1.18), 30 hops max, 60 byte packets 1 bogon (192.168.1.18) 0.559 ms 0.497 ms 0.445 ms [root@bogon ~]# telnet 192.168.1.18 1521 Trying 192.168.1.18... Connected to 192.168.1.18. Escape character is '^]'. [oracle@bogon ~]$ tnsping 192.168.1.18 TNS Ping Utility for Linux: Version 19.0.0.0.0 - Production on 13-MAY-2023 08:59:56 Copyright (c) 1997, 2022, Oracle. All rights reserved. Used parameter files: /u01/app/oracle/product/19.3.0/db_1/network/admin/sqlnet.ora Used HOSTNAME adapter to resolve the alias Attempting to contact (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.18)(PORT=1521))) OK (0 msec) 克隆的环境全部都关闭下防火墙，并禁用：
systemctl status firewalld systemctl stop firewalld systemctl disable firewalld 一切正常！
这个根因找到后着实有点丢人了，折腾半天居然就是最开始怀疑的防火墙问题，但却因为命令搞错误判了。
记得早些时候这个Linux6查看防火墙的命令在Linux7中执行，重定向是可以变成正确命令的。
再就是应该多查下，如果是类似下面的输出才是没有防火墙运行：
[root@db11g ~]# /sbin/iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination 不过troubleshooting的有意思之处也就在于此，你总不能每次都可以快速解决问题，哪怕是相对简单的问题，也可能因为一个疏忽而走不少弯路，但这个过程是有意思的！
