首先是第一次登录,这里主要谈登陆失败的情况: 我之前做过一个vps,然后听说日本的好,然后就把之前的那个服务器删了,删除后才发现日本机房的根本买不上,买上的很多也是IP被封了.当时自己还刷了很久linode网站,无果,最终选择了美国西海岸机房.据说除了日本机房最好选它.于是重新添加硬盘,Rebuild,等等,系统起来了,准备ssh登录了,然后就报错了,“That’s because SSH clients try to match the remote host with the known keys on your desktop computer. When you rebuild your Linode, the remote host key changes. “下面动手删了那一行:
Setting the hostname
CentOS 7 / Fedora version 18 and above
hostnamectl set-hostname hostname
Ubuntu 15.04 / Debian 8
hostnamectl set-hostname hostname
Setting the Timezone
Arch Linux and CentOS 7
timedatectl set-timezone Asia/Shanghai
Ubuntu / Debian
checking the time
Now try entering the following command to view the current date and time according to your server:
installing software update
Securing Your Server
Add a New User
The problem with logging in as root is that you can execute any command - even a command that could accidentally break your server. For this reason and others, we recommend creating another user account and using that at all times.
Open a terminal window and log in your linode server
Create the user by entering the following command.Replace
exampleuserto your desired username:
- Set the password for your new user by entering the following command. Replace
exampleuserwith your desired username:
- You will now need to edit your sudoers file to grant your new user the correct permissions. Enter the following command to open your sudoers file for editing:
- add an entry for your user below the root user, granting all permissions. Replace exampleuser with your username:
## Allow root to run any commands anywhere root ALL=(ALL) ALL exampleuser ALL=(ALL) ALL
- Enter the command
logoutAnd then log in your linode again by the following command,Replace exampleuser with your username, and the example IP address with your Linode’s IP address:
Using SSH Key Pair Authentication(SSH认证配对)
- linux Or Mac OS, Entering the following command in a terminal window
- copy the public key
~/.ssh/id_rsa.pubto your linode,you can entering the following command in a terminal window.Replace
example_userwith your username, and
123.456.78.90with your Linode’s IP address.
scp ~/.ssh/id_rsa.pub email@example.com:
- Create a directory for public key in your home directory (
/home/yourusername) by entering the following command ** on your linode: **
- move the file which is on your linode’s home directory to the directory your just create:
mv id_rsa.pub .ssh/authorized_keys
- Modify the permissions on the public key by entering the following commands, one by one, on your linode. Replace
example_userwith your username.
chown -R example_user:example_user .ssh chmod 700 .ssh chmod 600 .ssh/authorized_keys
Disabling SSH Password Authentication and Root Login(禁止SSH的密码登录和root登陆)
First, you’ll disable password authentication to require all users connecting via SSH to use key authentication. Next, you’ll disable root login to prevent the root user from logging in via SSH. These steps are optional, but are strongly recommended.
- Open the SSH configuration file for editing by entring the following command:
sudo vim /etc/ssh/sshd_config
PasswordAuthenticationand push Enter key, push
nto search the key word,change the keyword’s setting to
no,Verify that the line is uncommented by removing the # in front of line:
- Change the
noas shown below:
- save the configuration file (
:wq) and restart the SSH service to load the new configuration:
sudo systemctl restart sshd
sudo service ssh restart
Creating a Firewall
This step is optional, but we strongly recommend that you use the example below to block traffic to ports that are not commonly used. It’s a good way to deter would-be intruders! You can always modify the rules or disable the firewall later.
- Check your Linode’s default firewall rules by entering the following command:
sudo iptables -L
- Examine the output. If you haven’t implemented any firewall rules yet, you should see an empty ruleset, as shown below:
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
- Create a file to hold your firewall rules by entering the following command:
sudo vim /etc/iptables.firewall.rules
- We’ve created some basic rules to get you started. Copy and paste the rules shown below in to the
iptables.firewall.rulesfile you just created.
By default, the rules will allow traffic to the following services and ports: HTTP (80), HTTPS (443), SSH (22), and ping. All other ports will be blocked.
*filter # Allow all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0 -A INPUT -i lo -j ACCEPT -A INPUT -d 127.0.0.0/8 -j REJECT # Accept all established inbound connections -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # Allow all outbound traffic - you can modify this to only allow certain traffic -A OUTPUT -j ACCEPT # Allow HTTP and HTTPS connections from anywhere (the normal ports for websites and SSL). -A INPUT -p tcp --dport 80 -j ACCEPT -A INPUT -p tcp --dport 443 -j ACCEPT # Allow SSH connections # # The -dport number should be the same port number you set in sshd_config # -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT # Allow ping -A INPUT -p icmp --icmp-type echo-request -j ACCEPT # Log iptables denied calls -A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7 # Drop all other inbound - default deny unless explicitly allowed policy -A INPUT -j DROP -A FORWARD -j DROP COMMIT
Be sure to revise these rules if you add new services later.
- Optional: If you plan on using the Linode Longview service, add these additional lines above the
# Drop all other inboundsection:
# Allow incoming Longview connections -A INPUT -s longview.linode.com -j ACCEPT # Allow metrics to be provided Longview -A OUTPUT -d longview.linode.com -j ACCEPT
- Save the changes by pressing
:wqand then activate the firewall rules by entring the following command:
sudo iptables-restore < /etc/iptables.firewall.rules
- Recheck your Linode’s firewall rules by entering the following command:
sudo iptables -L
- Examine the output. The new ruleset should look like the one shown below:
Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT all -- anywhere anywhere REJECT all -- anywhere 127.0.0.0/8 reject-with icmp-port-unreachable ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED ACCEPT tcp -- anywhere anywhere tcp dpt:http ACCEPT tcp -- anywhere anywhere tcp dpt:https ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh ACCEPT icmp -- anywhere anywhere LOG all -- anywhere anywhere limit: avg 5/min burst 5 LOG level debug prefix "iptables denied: " DROP all -- anywhere anywhere Chain FORWARD (policy ACCEPT) target prot opt source destination DROP all -- anywhere anywhere Chain OUTPUT (policy ACCEPT) target prot opt source destination ACCEPT all -- anywhere anywhere
Now you need to ensure that the firewall rules are activated every time you restart your Linode.
CentOS 6.2 or 6.5:
/sbin/service iptables save
CentOS 7 or Fedora 20:
yum install -y iptables-services systemctl enable iptables systemctl start iptables
To save your current rule set use the following command:
Installing and Configuring Fail2Ban
Fail2Ban is an application that prevents dictionary attacks on your server. When Fail2Ban detects multiple failed login attempts from the same IP address, it creates temporary firewall rules that block traffic from the attacker’s IP address. Attempted logins can be monitored on a variety of protocols, including SSH, HTTP, and SMTP. By default, Fail2Ban monitors SSH only.
- Install Fail2Ban by entering the following command:
sudo yum install epel-release sudo yum install fail2ban
- Optionally, you can override the default Fail2Ban configuration by creating a new jail.local file. Enter the following command to create the file:
sudo nano /etc/fail2ban/jail.local
To learn more about Fail2Ban configuration options, see this article on the Fail2Ban website.
bantimevariable to specify how long (in seconds) bans should last.
maxretryvariable to specify the default number of tries a connection may be attempted before an attacker’s IP address is banned.
Control-xand then press
yto save the changes to the Fail2Ban configuration file.
Restart Fail2Ban by using
sudo service fail2ban restart.