Linux SysOps SSH connection speed optimization tips

Linux SysOps SSH connection speed optimization tips

SSH (Secure Shell) is a network protocol used to securely execute remote commands and Transfer files. As Linux system operation and maintenance personnel, we often need to use SSH to remotely connect to the server for management and maintenance. However, sometimes we may encounter the problem of slow SSH connection speed, which will affect our work efficiency. This article will introduce some tips for optimizing SSH connection speed and provide specific code examples.

1. Using the SSH configuration file

The SSH configuration file is located in /etc/ssh/sshd_config, where you can set some parameters to optimize the SSH connection speed. The following are some commonly used configuration options:

• TCPKeepAlive: This option controls whether to send TCP keepAlive packets to keep the SSH connection active. Setting this to "yes" improves connection speed and reduces the likelihood of disconnections.

TCPKeepAlive yes

• ClientAliveInterval and ClientAliveCountMax: These two options are used to detect idle connections and automatically disconnect them. The default interval is 0, which means this feature is disabled. ClientAliveInterval can be set to a certain interval (such as 60 seconds), and ClientAliveCountMax can be set to a certain number of times (such as 3 times) to keep the SSH connection active.

ClientAliveInterval 60
ClientAliveCountMax 3

• UseDNS: If the DNS service is not enabled in your network environment, you can set UseDNS to "no" to speed up the SSH connection.

UseDNS no

• Compression: Enabling data compression reduces the amount of data transferred, thereby increasing connection speeds. However, if your network has a lot of bandwidth, you may not need to enable this option.

Compression yes

2. Using SSH Agent Forwarding

SSH Agent Forwarding is a function that passes the SSH key on the local computer to the remote server, which can avoid multiple Enter your password once. Before using SSH Agent Forwarding, you need to ensure that the local computer has been configured with an SSH key.

On your local computer, just run the following command:

ssh-add

Then connect to the remote server via SSH. This avoids entering a password every time you connect and improves connection speed.

3. Use connection reuse

SSH connection reuse refers to creating a new session on an already established SSH connection without having to re-authenticate and establish a new one. connect. This can reduce the connection establishment time and increase the connection speed. You can add the following options to the SSH configuration file to enable connection reuse:

ControlMaster auto
ControlPath ~/.ssh/socket-%r@%h:%p

4. Adjust SSH encryption algorithm

By default, the encryption algorithm used by SSH is somewhat slow , the encryption algorithm can be adjusted to increase connection speed. In the SSH configuration file, the following options can be added or modified to a suitable encryption algorithm:

Ciphers aes128-ctr,aes192-ctr,aes256-ctr
MACs hmac-sha2-512,hmac-sha2-256
KexAlgorithms diffie-hellman-group-exchange-sha256

5. Optimize server-side configuration

On the server side, you can use the following methods To optimize SSH connection speed:

• Disable GSSAPI authentication: GSSAPI authentication can be disabled by adding the following configuration option to the SSHD configuration file.

GSSAPIAuthentication no
GSSAPICleanupCredentials no

• Limit the maximum number of connections: By limiting the maximum number of concurrent connections to the SSH server, you can reduce CPU and memory usage, thereby increasing connection speed.

MaxSessions 10

Summary:

Through the above optimization techniques and configuration examples, we can significantly improve the SSH connection speed, reduce unnecessary waiting time, and thus improve work efficiency. However, different environments and needs may require different optimization strategies, and it is recommended to adjust and test according to the actual situation.

Note: Before making any configuration changes, please ensure a backup of all configuration files and test whether the new configuration is working properly.

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