[root@b ~]# rpm -qa | grep telnet
telnet-0.17-64.el7.x86_64
telnet-server-0.17-64.el7.x86_64
[root@b ~]# chkconfig --list | grep telnet
注：該輸出結果只顯示 SysV 服務，並不包含
原生 systemd 服務。SysV 配置數據
可能被原生 systemd 配置覆蓋。
要列出 systemd 服務，請執行 'systemctl list-unit-files'。
查看在具體 target 啟用的服務請執行
'systemctl list-dependencies [target]'。
[root@b ~]# systemctl list-unit
list-unit-files list-units
[root@b ~]# systemctl list-unit-files | grep telnet
telnet@.service static
telnet.socket disabled
[root@b ~]# systemctl start retelnet.socket
Failed to start retelnet.socket: Unit not found.
[root@b ~]# systemctl restart telnet.socket
[root@b ~]# systemctl enable telnet.socket
Created symlink from /etc/systemd/system/sockets.target.wants/telnet.socket to /usr/lib/systemd/system/telnet.socket.
[root@b ~]# systemctl list-unit-files | grep telnet
telnet@.service static
telnet.socket enabled
[root@b ~]# chkconfig telnet.socket on
服務 telnet.socket 信息讀取出錯：沒有那個文件或目錄
[root@b ~]# chkconfig sshd on #centos 7不在支持chkconfig方式設置開機自啟動
注意：正在將請求轉發到“systemctl enable sshd.service”。
[root@b ~]# firewall-cmd --list-services #查看當前開啟了哪些端口
dhcpv6-client ssh telnet
[root@b ~]# firewall-cmd --get-services #查看還可以開啟哪些服務
RH-Satellite-6 amanda-client amanda-k5-client bacula bacula-client bgp bitcoin b
itcoin-rpc bitcoin-testnet bitcoin-testnet-rpc ceph ceph-mon cfengine condor-col
lector ctdb dhcp dhcpv6 dhcpv6-client dns docker-registry docker-swarm dropbox-l
ansync elasticsearch freeipa-ldap freeipa-ldaps freeipa-replication freeipa-trus
t ftp ganglia-client ganglia-master git gre high-availability http https imap im
aps ipp ipp-client ipsec irc ircs iscsi-target jenkins kadmin kerberos kibana kl
ogin kpasswd kprop kshell ldap ldaps libvirt libvirt-tls managesieve mdns minidl
na mongodb mosh mountd ms-wbt mssql murmur mysql nfs nfs3 nmea-0183 nrpe ntp ope
nvpn ovirt-imageio ovirt-storageconsole ovirt-vmconsole pmcd pmproxy pmwebapi pm
webapis pop3 pop3s postgresql privoxy proxy-dhcp ptp pulseaudio puppetmaster qua
ssel radius redis rpc-bind rsh rsyncd samba samba-client sane sip sips smtp smtp
-submission smtps snmp snmptrap spideroak-lansync squid ssh syncthing syncthing-
gui synergy syslog syslog-tls telnet tftp tftp-client tinc tor-socks transmissio
n-client upnp-client vdsm vnc-server wbem-https xmpp-bosh xmpp-client xmpp-local
xmpp-server zabbix-agent zabbix-server
[root@b ~]# firewall-cmd --add-service=telnet #添加需要通過防火牆的服務
Warning: ALREADY_ENABLED: 'telnet' already in 'public'
success
[root@b ~]# firewall-cmd --permanent --add-service=telnet #永久開放一個服務，加上permanent，開啟自動放行
Warning: ALREADY_ENABLED: telnet
success
[root@b ~]# firewall-cmd --reload #重新加載防火牆並保留狀態信息
success
[root@b ~]# firewall-cmd --list-ports #查看所有開放的端口
[root@b ~]# firewall-cmd --list-all #查看防火牆的詳細規則
[root@b ~]# firewall-cmd --list-service #查看所有開放的服務
[root@b ~]# firewall-cmd --add-port=2049/tcp --permanent #添加一個放行端口
[root@b ~]# firewall-cmd --add-service=nfs --permanent #添加一個放行的服務
[root@b ~]# firewall-cmd --query-port=2049/tcp #查詢一個端口是否開放
[root@b ~]# firewall-cmd -query-service=nfs #查詢一個服務是否放行
windows客戶端cmd驗證:
服務器重啟后，客戶端驗證正常。