--- title: "Support for remote access error (Linux)" slug: "server-ts-remote-lin-vpc" tags: ["troubleshooting", "vpc", "Server", "remote"] updated: 2026-09-17T09:18:00Z published: 2026-09-17T09:18:00Z canonical: "guide.ncloud-docs.com/server-ts-remote-lin-vpc" --- > ## Documentation Index > Fetch the complete documentation index at: https://guide.ncloud-docs.com/llms.txt > Use this file to discover all available pages before exploring further. # Support for remote access error (Linux) Available in VPC This document describes how to troubleshoot symptoms of server remote access errors in the Linux environment. ## Check Linux server remote access settings To remotely access the Linux server, ensure that the IP or subnet of the server to access is applied to the ACG. If not applied, see [Set ACG](/docs/en/server-acg-vpc#ACG%EC%84%A4%EC%A0%95) and change the ACG settings. If there is no problem in ACG settings, check the following matters: - Check if the server allows access to SSH/RDP service. Note If the port setting on the server has been changed, update the settings accordingly. - SSH service: TCP, allowed port 22 - RDP service: TCP, allowed port 3389 - Check the port forwarding settings. - If both public IP and port forwarding are set simultaneously, you cannot communicate through a public IP. When using a public IP, remove the port forward settings. Even if no problem is found as a result of checking the above, the SSH service port or the RDP service port may not work normally for various causes. In this case, the **[Server connection console]** button is enabled in the server information of NAVER Cloud Platform console. To resolve this issue, see [Troubleshooting Linux server remote access errors](/docs/en/server-ts-remote-lin-vpc#Linux%EC%84%9C%EB%B2%84%EC%9B%90%EA%B2%A9%EC%A0%91%EC%86%8D%EC%98%A4%EB%A5%98%ED%95%B4%EA%B2%B0). ![server-ts-remote-lin-classic_image01_ko](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-classic_image01_en.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) ## Troubleshooting Linux server remote access errors If Linux server remote access errors occur, see the OS-specific solutions to troubleshoot them. - [NAVIX 9 / RockyLinux 8/9](/docs/en/server-ts-remote-lin-vpc#Navix9Rocky89) - [CentOS 7](/docs/en/server-ts-remote-lin-vpc#CentOS7) - [Ubuntu 18.04](/docs/en/server-ts-remote-lin-vpc#Ubuntu1804) ### NAVIX 9, Rocky Linux 8/9 #### 1. Check daemon status Check sshd daemon status - Check that the daemon is `running` normally. ``` [root@navix ~]# systemctl status sshd ● sshd.service - OpenSSH server daemon Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; preset: enabled) Active: active (running) since Thu 2025-12-11 10:26:30 KST; 1 month 2 days ago Docs: man:sshd(8) man:sshd_config(5) Main PID: 643 (sshd) Tasks: 1 (limit: 48884) Memory: 83.2M CPU: 1h 7min 43.161s CGroup: /system.slice/sshd.service └─643 "sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups" ``` - If the daemon is `inactive`, try to `start`. If an error occurs, check the server log to ensure that the sshd daemon can properly `start`. Check that the sshd daemon is listening on port 22. ``` [root@navix ~]# netstat -ntlp |grep sshd tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 643/sshd: /usr/sbin tcp6 0 0 :::22 :::* LISTEN 643/sshd: /usr/sbin ``` #### 2. Check routing Without a default route for `eth0`, it cannot communicate. Check the static route status for `eth0`. ``` [root@navix ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.0.1 0.0.0.0 UG 100 0 0 eth0 192.168.0.0 0.0.0.0 255.255.0.0 U 100 0 0 eth0 ``` #### 3. Check ssh root login permissions A configuration item called `PermitRootLogin yes` must be present to log in with the ssh root account. The example below shows a case where the configuration is present in the `/etc/ssh/sshd_config.d/01-permitrootlogin.conf` file. Check if the settings are correct. ``` [root@navix ~]# grep -r PermitRootLogin /etc/ssh/* /etc/ssh/sshd_config:#PermitRootLogin prohibit-password /etc/ssh/sshd_config:# the setting of "PermitRootLogin without-password". /etc/ssh/sshd_config.d/01-permitrootlogin.conf:PermitRootLogin yes ``` ### CentOS 7 To troubleshoot a remote access error on CentOS 7 in Linux environment, perform the following steps in order. - [1. Check daemon status](/docs/en/server-ts-remote-lin-vpc#1%EB%8D%B0%EB%AA%AC%EC%83%81%ED%83%9C%ED%99%95%EC%9D%B8) - [2. Check status of hosts.deny setting](/docs/en/server-ts-remote-lin-vpc#2hostsdeny%EC%84%A4%EC%A0%95%EC%83%81%ED%83%9C%ED%99%95%EC%9D%B8) - [3. Check firewall](/docs/en/server-ts-remote-lin-vpc#3%EB%B0%A9%ED%99%94%EB%B2%BD%ED%99%95%EC%9D%B8) - [4. Check routing](/docs/en/server-ts-remote-lin-vpc#4%EB%9D%BC%EC%9A%B0%ED%8C%85%ED%99%95%EC%9D%B8) - [5. Check authority problem](/docs/en/server-ts-remote-lin-vpc#5%EA%B6%8C%ED%95%9C%EC%9D%B4%EC%8A%88%ED%99%95%EC%9D%B8) #### 1. Check daemon status To check the daemon status, perform the following steps in order. 1. Run the following command to check if the daemon is properly `running`. ``` systemctl status sshd ``` ![server-ts-remote-lin-vpc_image02](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image02.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) - If the daemon is `inactive`, try to `start`. If an error occurs, check the server log to ensure that the sshd daemon can properly `start`. 2. Run the following command to check if ssh is `LISTEN` on port 22. ``` netstat -nap | grep ssh ``` ![server-ts-remote-lin-vpc_image03](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image03.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) Note - The default setting on NAVER Cloud Platform's server is port 22. - If the port setting on the server has been changed, update the settings accordingly. 3. Run the following command to check if the port and `ListenAddress` have any settings. ``` vi /etc/ssh/sshd_config ``` ![server-ts-remote-lin-vpc_image04](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image04.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) - The default setting is annotated. #### 2. Check status of hosts.deny setting The `hosts.allow` and `hosts.deny` files control the service to allow or block specific clients only. Check if the `hosts.allow` and `hosts.deny` files have any settings. The default setting is annotated. ![server-ts-remote-lin-vpc_image05](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image05.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) Note - The `/etc/hosts.allow` and `/etc/hosts.deny` files control only `tcp_wrappers`. Apply the rules in the following order: 1. Set to allow what is defined in the `/etc/hosts.allow` file. 2. Set to block what is not defined in the `/etc/hosts.allow` file but is defined in `/etc/hosts.deny` the file. 3. Set to allow what is defined in both `/etc/hosts.allow` and `/etc/hosts.deny` files. - It can control certain services of the daemon managed by `tcp_wrappers` and `xinetd`. Example: ssh, telnet, ftp #### 3. Check firewall Check the firewall with the following: **a. iptables** If `iptables.service` is installed, the daemon is also affected by rules even in the `inactive` status and excludes the rules to block ssh in iptables rules. No applied rules in default setting. ![server-ts-remote-lin-vpc_image06](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image06.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) **b. firewalld** The `firewalld` is not applied if the daemon is `inactive`. If you need to run `firewalld`, exclude the rule to block ssh. No applied rules in default setting. ![server-ts-remote-lin-vpc_image07](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image07.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) #### 4. Check routing Without a default route for `eth0`, it cannot communicate. Check the static route status for `eth0` and `169.254.0.0/16`. ![server-ts-remote-lin-vpc_image09](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image09.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) #### 5. Check authority problem Depending on the ssh config, remote access of the root account may be blocked. If unable to access through root, try connecting with a regular account. If you don't have a regular access account, enable the server connection console to access root. ### Ubuntu 18.04 To troubleshoot a remote access error on Ubuntu 18.04 in Linux environment, perform the following steps in order. - [1. Check daemon status](/docs/en/server-ts-remote-lin-vpc#1%EB%8D%B0%EB%AA%AC%EC%83%81%ED%83%9C%ED%99%95%EC%9D%B82) - [2. Check status of hosts.deny setting](/docs/en/server-ts-remote-lin-vpc#2hostsdeny%EC%84%A4%EC%A0%95%EC%83%81%ED%83%9C%ED%99%95%EC%9D%B82) - [3. Check firewall](/docs/en/server-ts-remote-lin-vpc#3%EB%B0%A9%ED%99%94%EB%B2%BD%ED%99%95%EC%9D%B82) - [4. Check routing](/docs/en/server-ts-remote-lin-vpc#4%EB%9D%BC%EC%9A%B0%ED%8C%85%ED%99%95%EC%9D%B82) - [5. Check authority problem](/docs/en/server-ts-remote-lin-vpc#5%EA%B6%8C%ED%95%9C%EC%9D%B4%EC%8A%88%ED%99%95%EC%9D%B82) #### 1. Check daemon status To check the daemon status, perform the following steps in order. 1. Run the following command to check if the daemon is properly `running`. ``` systemctl status sshd ``` ![server-ts-remote-lin-vpc_image10](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image10.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) - If the daemon is `inactive`, try to `start`. If an error occurs, check the server log to ensure that the sshd daemon can properly `start`. 2. Run the following command to check if it is `LISTEN` on the ssh port. ``` netstat -nap | grep ssh ``` ![server-ts-remote-lin-vpc_image11](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image11.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) Note - The default setting on NAVER Cloud Platform's server is port 22. - If the port setting on the server has been changed, update the settings accordingly. 3. Run the following command to check if the port and `ListenAddress` have any settings. ``` vi /etc/ssh/sshd_config ``` ![server-ts-remote-lin-vpc_image12](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image12.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) - The default setting is annotated. #### 2. Check status of hosts.deny setting The `hosts.allow` and `hosts.deny` files control the service to allow or block specific clients only. Check if the `hosts.allow` and `hosts.deny` files have any settings. The default setting is annotated. ![server-ts-remote-lin-vpc_image13](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image13.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) Note - The `/etc/hosts.allow` and `/etc/hosts.deny` files control only `tcp_wrappers`. Apply the rules in the following order: 1. Set to allow what is defined in the `/etc/hosts.allow` file. 2. Set to block what is not defined in the `/etc/hosts.allow` file but is defined in `/etc/hosts.deny` the file. 3. Set to allow what is defined in both `/etc/hosts.allow` and `/etc/hosts.deny` files. - It can control certain services of the daemon managed by `tcp_wrappers` and `xinetd`. Example: ssh, telnet, ftp #### 3. Check firewall Check the firewall with the following: **a. iptables** If `iptables.service` is installed, the daemon is also affected by rules even in the `inactive` status and excludes the rules to block ssh in iptables rules. No applied rules in default setting. ![server-ts-remote-lin-vpc_image14](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image14.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) **b. ufw** The `ufw` is not applied if the daemon is `inactive`. If you need to run `ufw`, exclude the rule to block ssh. No applied rules in default setting. ![server-ts-remote-lin-vpc_image15](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image15.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) #### 4. Check routing Without a default route for `eth0`, it cannot communicate. Check the static route status for `eth0` and `169.254.0.0/16`. ![server-ts-remote-lin-vpc_image30](https://cdn.document360.io/6998976f-9d95-4df8-b847-d375892b92c2/Images/Documentation/server-ts-remote-lin-vpc_image30.png?sv=2026-02-06&spr=https&st=2026-10-27T16%3A29%3A31Z&se=2026-10-27T17%3A29%3A31Z&sr=c&sp=r&sig=AmSDL1nzQ8sv8dg%2F%2F5Y0Nh6PtO7xLfoQ%2By03nVztWX0%3D) #### 5. Check authority problem Depending on the ssh config, remote access of the root account may be blocked. If unable to access through root, try connecting with a regular account. If you don't have a regular access account, enable the server connection console to access root.