CentOS 7 下 Telnet 远程 root 登录

Telnet 服务 && 依赖包安装

下载安装包

• 下载 telnet-server

https://rpmfind.net/linux/centos/7.9.2009/os/x86_64/Packages/telnet-server-0.17-65.el7_8.x86_64.rpm

• 下载 xinetd

https://rpmfind.net/linux/centos/7.9.2009/os/x86_64/Packages/xinetd-2.3.15-14.el7.x86_64.rpm

安装安装包

• 安装 telnet-server

[root@localhost ~]# rpm -ivh telnet-server-0.17-65.el7_8.x86_64.rpm 
warning: telnet-server-0.17-65.el7_8.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...1:telnet-server-1:0.17-65.el7_8    ################################# [100%]

• 安装 xinetd

[root@localhost ~]# rpm -ivh xinetd-2.3.15-14.el7.x86_64.rpm 
warning: xinetd-2.3.15-14.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...1:xinetd-2:2.3.15-14.el7           ################################# [100%]

配置 && 启动服务

关闭防火墙

[root@localhost ~]# systemctl disable firewalld
[root@localhost ~]# systemctl stop firewalld

关闭 SELinux

# 临时关闭
[root@localhost ~]# setenforce 0

修改安全文件

# 增加配置
[root@localhost ~]# cat <<  EOF >> /etc/securetty
pts/0
pts/1
EOF

修改 pam 模块 telnet 权限

# 修改前
[root@localhost ~]# grep 'pam_securetty.so' /etc/pam.d/remote 
auth       required     pam_securetty.so# 修改后 -- 注释掉
[root@localhost ~]# grep 'pam_securetty.so' /etc/pam.d/remote 
# auth       required     pam_securetty.so

配置 telnet-server 参数

# 新建文件
[root@localhost ~]# cat << EOF > /etc/xinetd.d/telnet
service telnet
{flags = REUSEsocket_type = streamwait = nouser = rootserver = /usr/sbin/in.telnetdlog_on_failure += USERIDdisable = no
}
EOF

启动 telnet-server

[root@localhost ~]# systemctl start telnet.socket

启动 xinetd

[root@localhost ~]# systemctl start xinetd

验证 root 通过 telnet 远程登陆

验证 telnet 服务状态

[root@localhost ~]# systemctl status telnet.socket
● telnet.socket - Telnet Server Activation SocketLoaded: loaded (/usr/lib/systemd/system/telnet.socket; disabled; vendor preset: disabled)Active: active (listening) since Wed 2022-11-02 19:04:00 CST; 26s agoDocs: man:telnetd(8)Listen: [::]:23 (Stream)Accepted: 0; Connected: 0

验证 xinetd 服务状态

[root@localhost ~]# systemctl status xinetd -l
● xinetd.service - Xinetd A Powerful Replacement For InetdLoaded: loaded (/usr/lib/systemd/system/xinetd.service; enabled; vendor preset: enabled)Active: active (running) since Wed 2022-11-02 19:04:06 CST; 1min 1s agoProcess: 1739 ExecStart=/usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid $EXTRAOPTIONS (code=exited, status=0/SUCCESS)Main PID: 1740 (xinetd)CGroup: /system.slice/xinetd.service└─1740 /usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid

验证 telnet 端口

[root@localhost ~]# ss -ntlp | grep 23
LISTEN     0      128       [::]:23        [::]:*       users:(("systemd",pid=1,fd=26))

验证 root 通过 telnet 登录

[C:\~]$ telnet 192.168.68.129Connecting to 192.168.68.129:23...
Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.Kernel 3.10.0-1127.el7.x86_64 on an x86_64
localhost login: root
Password: 
Last login: Wed Nov  2 19:02:11 from 192.168.68.1

参考

• Telnet 远程 root 登录 CentOS