Does Changing Ssh Port Improve Security

While changing the SSH port from its default setting of 22 to a non-standard port can improve security, it’s a rather minimal gain. This strategy primarily helps prevent your system from being targeted by automated scripts which typically scan for weak SSH credentials on port 22. By moving to a less common port you make your system less visible to these broad but shallow scans. However, it should not be your sole layer of security as a dedicated attacker who specifically targets your system could easily discover the new port by performing comprehensive port scans.

Further, changing your SSH port also brings inconveniences, namely with configurations. Many tools assume that SSH is operating on port 22 and may require additional configuration to function properly with a different port. You’ll also need to recall or document this custom port number for ongoing use.

For a truly secure setup, a more robust approach would involve better practices like using key-based authentication instead of password-based, disabling root logins, and maintaining current security patches [source]. Making these changes will provide a stronger protection than merely altering the SSH port. Changing the SSH port can only help mitigate the risk of easy attacks but is not sufficient as a standalone solution.

# How to change the SSH port
# Open the SSH daemon's configuration file
sudo nano /etc/ssh/sshd_config

# Find the line that specifies the port, uncomment it by deleting the '#' before 'Port 22', and change the '22' to your desired port number.
Port 22

# Save changes and close the file using CTRL-X, Y, then ENTER.
# Restart the SSH daemon to apply the changes.
sudo systemctl restart ssh

Remember, changing the SSH port should be considered a part of your overall security strategy if you believe it to be beneficial in your specific context. It might add another layer of complexity for potential attackers but it isn’t a foolproof or universally recommended security measure. Always keep security measures in balance with the usability needs of your system.The Secure Shell (SSH) protocol is a method for managing network services over an unsecured network securely. SSH provides secure access to the shell environment on a remote machine, which is typically guided by port 22.

However, in our interconnected world, where scanning tools are getting more advanced, hackers often aim at default ports like the port 22. If they find these ports open, they attack using brute force or other methods.

So, does changing the default port improve security? To answer this question, let’s first analyze what happens when we change the SSH port:

Factors Influencing SSH Port Change Impact

– Security through obscurity: Changing the SSH port from 22 to some obscure high number was defined as “security through obscurity” and was traditionally seen as a weak security control. However, given it takes no effort to check for services running on well known ports like 22, moving away from these can put you off the radar of many automated attacks.
– Avoiding unnecessary traffic: By changing ports, you repel unwelcome visitors who knock on your SSH door without valid intentions. It prevents your logs from being cluttered with failed login attempts.
– Avoiding automated attacks: Most automated scripts target default SSH ports. Therefore, by changing the SSH port, you get under the radar of most botnets and automated attacks.

To answer our question: yes, changing your SSH port can improve its security; however, remember that this should not be the only protection mechanism. A comprehensive approach to SSH security might include:

– Implementing strong password policies.
– Using key based authentication.
– Limiting root logins.
– Employing a firewall to filter incoming connections.
– Monitoring and analyzing logs regularly.

Let’s illustrate how to correctly change the SSH server port in a Linux environment.

# Open the sshd_config file with any text editor. For instance:
nano /etc/ssh/sshd_config
# Once inside, locate this line: #Port 22
# Uncomment it and change 22 to your chosen port number, say 1234.
Port 1234 
# Save the changes and exit the text editor.
# Restart the SSH server to implement changes. On Ubuntu, for example:
sudo systemctl restart ssh

Therefore, while not a silver bullet or primary solution, changing your SSH port can indeed enhance your server’s security by making it less visible to automated attacks. This measure allies with others to form a robust shield against unauthorized access and breaches Source.

Secure Shell (SSH) provides a means for secure remote access to a host machine, which is often used by administrators or users to manage their systems. By default, SSH listens on port 22. Some argue changing the default SSH port (port 22) increases security. But does it really improve your system’s security?

The Concept Behind Changing SSH Port

The idea behind shifting from the default port seems to make sense at first glance: if you move your SSH service to another, less well-known port, automated scanners — which typically target widely-used ports like 22 — won’t find you. As such, the number of unauthorized login attempts may be significantly reduced.

Obfuscation Vs. Security

However, it is worth noting that this is not a real security improvement per se; rather, it’s obfuscation. Obfuscation, while it might make a system harder to detect, should not be confused with solid protective measures, since determined attackers can easily bypass it. Essentially, while a changed port may deter casual malicious users, an advanced attacker who specifically targets your server will use a full-port scan and find your SSH service eventually.

Necessity Of Advanced Protective Measures

In other words, changing the default SSH port is akin to ‘security by obscurity’, and while it may reduce noise from automated attacks, it doesn’t properly protect your system. A strong security posture requires more advanced protective measures, such as:

• Using strong, complex passwords: Better yet, disable password authentication altogether and use key-based authentication.
• Implementing a firewall: This will limit access to SSH, so only trusted IP addresses can connect to the service.
• Setting up intrusion detection and prevention systems: They can detect and block brute force and dictionary attacks.
• Regularly patching and updating your systems: This ensures that the latest vulnerabilities have been addressed.

Too often, small steps like moving your SSH port are used as a panacea, leading server admins to disregard other, more important security measures. Instead of relying solely on port transposition for protection, administrators should see it as part of a broader, multi-faceted approach to SSH security.

Inference from Various Viewpoints

From a security analyst perspective, changing SSH port merely reduces the volume of logs for invalid logon attempts. However, take note that some security standards, such as PCI DSS, discourage the practice of changing default SSH ports. It’s viewed as a weak attempt to achieve security through obscurity, which is generally discouraged in the infosec community.

In a nutshell, while adjusting SSH’s default port can reduce log clutter, it isn’t a comprehensive security solution. Instead, focus on implementing proven security practices mentioned above and keep your systems updated to ensure robust protection for your services.
Reference:
ssh.com

Example of changing SSH port:

 # Backup the original sshd configuration
 cp /etc/ssh/sshd_config /etc/ssh/sshd_config.original
 chmod a-w /etc/ssh/sshd_config.original

 # Edit the sshd configuration
 nano /etc/ssh/sshd_config

 # Change the line Port 22 to another port, say 2222
 Port 2222

 # Save the changes
 Ctrl + X, then Y to confirm saving the changes.

 # Restart the sshd service
 systemctl restart sshd

It’s indeed a commonly asked question by system administrators whether changing the default SSH port number improves server security. To approach this, let’s dissect the issue and analyze the possible outcomes in terms of server security.

By default, SSH listens on port 22. This is a widely known fact which makes it one of the first targets for hackers. By changing the default port number, you can stop automated bot scans that are specifically targeting port 22. However, it’s important to understand that simply changing the SSH port isn’t a foolproof security measure but rather a type of obfuscation meant to reduce noise from logs generated by automated scanning bots.

Let’s look at the main points:

Pros of Changing SSH Port

– It reduces the noise in the logs by avoiding generic scanning bots who only target the default port 22.
– An attacker may not immediately identify the port SSH service runs on, hence improving obscurity.

Here’s how you change the port of your SSH:

Firstly, open your sshd config file:

sudo nano /etc/ssh/sshd_config

Then, find a line written as #Port 22, remove the hashtag, and change 22 to any port you prefer. Remember to avoid using reserved ports (0-1023). After you’re done, restart your SSH server.

service ssh restart

Cons of Changing SSH Port

– If an attacker performs a careful scan of all ports or a large range, they will identify SSH service, regardless of the port it runs on.
– Changing the port frequently can complicate access for authorized users.
– Port numbers above 1024 can be used by any user and many services, creating potential conflicts.
– Certain networks might restrict outgoing traffic to selected port numbers. Non-standard SSH port might limit or prevent your SSH accessibility from such networks.

Overall, while changing your SSH port can provide some level of obscurity, it doesn’t substantially improve the overall security of your server. It should not be considered a primary security measure, but more of a secondary—or even tertiary—measure to keep your logs clean and make an attacker’s work slightly harder.

At the end of the day, implementing robust security measures such as key-based authentication, disabling root logins, configuring an intrusion detection/prevention system, and employing firewall rules is far more effective than mere port obfuscation. For example, setting up key-based authentication can be done by generating a new SSH key pair using the command:

ssh-keygen -t rsa

Then, copy your public key to the SSH server with:

ssh-copy-id username@serverip_or_hostname

This is always recommended as a more reliable and proven way of protecting your SSH access.source. So when talking about server security, always prioritize securing the service itself rather than obscuring the port that it operates on. The right balance of security practices will definitely bring robust protection to your precious servers.

Whether changing your SSH (Secure Shell) port improves security is a debate that has its merits on both sides of the argument. On one hand, shifting from the default SSH port (22) can help reduce the surface area for brute force attacks. This technique is often termed as “Security through obscurity”. However, critics argue that this step merely slows down attackers and does nothing to prevent a determined attacker from discovering the new port.

Regardless, changing your SSH port can be an effective deterrent against automated attacks or scripts that specifically target the default SSH port. Here are the steps to change your SSH port effectively:

Backup Your Current SSH Configuration

This is crucial in case anything goes wrong during the process. You can make a backup using the

cp

command:

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.bak

Edit SSH Configuration File

You’ll find the SSH configuration file at

/etc/ssh/sshd_config

. Use your preferred text editor (vi, nano, etc.) to open and edit it:

sudo nano /etc/ssh/sshd_config

Change the Port line

The line you need to look for in the SSH config file is “Port 22”. For instance, if you want to change the port to 2022, edit the file like below:

Port 2022

Note: Make sure to choose a port number over 1024, as ports below that are considered “well known ports” and may be used by other services.

Save Your Changes

Depending upon the editor, saving files would be different. With nano, you would use CTRL+X, then press Y when prompted about saving the modified buffer, and then hit Enter to confirm the filename to write.

Restart SSH Service

In order for the changes to take effect, you must restart the SSH service with:

sudo systemctl restart sshd

All your future SSH connections need to denote the custom port number:

ssh user@host -p 2022

Please be informed that while this does add an extra layer of protection (however minimal), more rigorous ways of securing SSH include applying rules through Access Control, using public key authentication instead of passwords, or even leveraging two-factor authentication mechanisms. Finally, always remember that there is indeed no substitute for a strong, hard to guess password reinforced with multi-factor authentication.

References:
TecMint: How to Change SSH Port in Linux,
Ubuntu Community Help: Configuring OpenSSH

As a professional coder, I often ponder about several ways to enhance system security and safety, and one such topic question that comes up frequently is: Does changing SSH (Secure Shell) port improve security? To answer this, we should carefully analyze the implications of this change.

The primary purpose of changing your SSH port is to deter unauthorized entry to a remote system from robots or automated attacks, specifically those utilizing default ports like 22 for targeting. This practice is often referred to as “Security through obscurity.” However,

This does not fundamentally augment your system’s security.

Key Reasons:

• No substantial barrier: Changing the SSH port can only provide a thin additional obscurity layer but does not present any significant barrier to an actual attacker. Attackers who are genuinely determined can easily scan all ports on a system using tools like nmap to detect SSH by its response regardless of the port it’s hiding behind.

  nmap -p- localhost

• Privacy tradeoff: Every move towards security comes with potential tradeoffs. While you might dodge basic bots hunting for port 22, you might stick out to more sophisticated observers who notice the anomalously high port number. Obscurity can work both ways with this technique.
• Maintenance overhead: Deviating from standardized ports may add unnecessary complexity in maintaining configurations across different systems in a network, causing more human errors in security settings.

A More Robust Security Approach

For truly improving the security of SSH server, I always suggest focusing on robust and proven methods:

• Regular updates: Keep your system and SSH server updated. This ensures any existing vulnerabilities are patched.
• Passwordless login: Disable password-based logins by implementing public-key authentication instead.
• Two-factor authentication: Set up two-factor authentication for highly secure environments.
• Firewalls and filters: Use network firewalls and packet filters to restrict access to your SSH server only to trusted users, machines, and networks.
• Monitoring: Use intrusion detection systems(IDS) to monitor SSH logins attempts, successful logins, and activities.

In conclusion, if you wish to deter non-targeted auto-attacks at least to some extent, changing your SSH port can be an option, but it doesn’t provide substantial security enhancement against determined attackers. It is advisable not to rely solely on this method, but instead implement robust security measures as suggested.

You can have further reading from SSH.com which provides more details on secure shell (SSH).

# A basic port scanning command using Nmap
nmap -p- TARGET_IP

# An ssh command specifying a custom port
ssh -p CUSTOM_PORT user@your-server

# Example of ssh config file with a custom port
Host YourServer
    HostName your-server.example.com
    Port CUSTOM_PORT
    User your-user-name

# /etc/ssh/sshd_config
PasswordAuthentication no
ChallengeResponseAuthentication no
UsePAM no
PermitRootLogin prohibit-password

Changing the port for Secure Shell (SSH) is widely discussed as a potential measure to enhance security. Albeit not an all-encompassing solution by itself, when combined with other practices, it can contribute to your overall server protection.

// Changing the SSH port in the /etc/ssh/sshd_config file
Port 2222

By altering the default port (usually, 22), you make yourself less visible to automated attacks or bots. These threats generally target default ports because of the multitude of servers that use them. The rationale here is obscurity. But while it’s true that burglars will look for open main doors first, experts warn against relying solely on security through obscurity.

A number of potential threats remain even after modifying your SSH port:

1. Targeted Attacks: If attackers are intentionally going after your server, changing the SSH port may not deter them. Tools such as nmap can scan and discover all open ports.
2. Brute-Force Attacks: While moving away from the default port tends to reduce the likelihood of random brute-force attacks, it does nothing against dedicated ones. An attacker who’s aware of your SSH port can still launch a brute-force attack on it.
3. Misconfigurations: Even on a non-default port, mistakes in configuration, such as permitting root logins or allowing weak passwords, can render your SSH vulnerable.
4. Zero-day Vulnerabilities: Unknown vulnerabilities in SSH can be exploited regardless of the port it operates on until these gaps are discovered and patched.

This analysis isn’t a discouragement against changing your SSH port—it definitely has benefits. It’s important, however, to recognize what it does and does not protect against.

To supplement SSH port modification, consider implementing these security measures:

* Implement Public/Private Key Authentication: By disabling password logins, you can significantly deter brute-force attempts.
* Deploy Firewalls: Control which IPs have access to your server at all—the fewer the better.
* Use Fail2Ban: This tool bans IPs that show signs of brute-force attacks against you.
* Regular Updates & Patches: Keeping your SSH updated ensures you’re protected against known vulnerabilities.

In terms of security, the change of SSH port would not, categorically, improve your system’s defense mechanisms. Rather, it contributes towards a multi-layered security strategy required for effective protection. Obtaining a solid understanding of each security measure’s potential and limitations — SSH port changing included — paves the way for a stronger stance against cyber threats.

For more detailed information, here is a good article on enhancing SSH security: OpenSSH Server Best Practices.Dipping my toes into the pool of Secure Shell (SSH), I came across an interesting question: Does changing the SSH port improve security? Well, the answer is quite nuanced. In summary, modifying SSH ports might bring certain nominal enhancements to your system’s security, but it is not a silver bullet solution.

Let us understand why by diving deep into its implications and consequences:

Security through Obscurity
Altering the default SSH port, commonly 22, is often seen as a means to increase security by obfuscating it from potential attackers. This falls under the category of security through obscurity. It simply makes things slightly more difficult for unskilled hackers who only know about the default port. While it does reduce noise in logs and reduces the instances of automated hacking attempts, it’s not a lethal weapon against determined or proficient assaults.

# Alter the SSH port in sshd_config

Port 2022

The Double-edged Sword of altering SSH Ports
One significant downside to this is that moving away from standard conventions may confuse legitimate users and services.

• Tools that depend on the SSH service might break and will require further configurations.
• It further indicates additional administrative overhead. For instance, remembering to specify a custom port every time you access SSH can be inconvenient and error-prone, particularly when dealing with many servers.
• Moreover, it might conflict with other applications using that same port, leading to unnecessary complications.

# Accessing SSH on a non-standard port

ssh -p 2022 user@hostname

A False Sense of Security
Being overwhelmed by a false sense of security is easy when implementing a low-level change like this. Nevertheless, it is vital not to get complacent regarding security eventually. Understand that altering the SSH port adds a very minimal additional layer of security. The crucial actual implementing robust security practices includes public key authentication, password-less logins, and enabling SSH configurations to disallow root logins, to name a few.

An Overall Minimal Impact
Does it hurt to change your SSH port? No, not really, unless it influences your dependencies. However, does it substantially improve your security situation? Again, the answer is no. It is at best a subpar defense strategy that won’t stand up to concentrated intrusion attempts but does help tone down the noise.

To reiterate, altering the SSH port should only be contemplated as supplementary to implementing a concrete security protocol rather than being a primary defense strategy. It’s always advisable to employ comprehensive multi-faceted security defenses which enclose continuous vigilance and maintenance, encryption, back-ups, stringent permissions, etc., all while keeping software versions up-to-date.

In conclusion, while the benefits do not largely outweigh the potential consequences, altering the default SSH port isn’t necessarily a bad move; however, it shouldn’t be the sole action taken towards securing your systems. You’d be well-served by focusing more on practices that genuinely secure your system, like those mentioned above.

Remember: There’s no perfect. Every bit helps. Always aim for improvement!When it comes to the secure shell protocol, otherwise known as SSH, there are indeed many best practices that users must revisit. However, a common question seems to be focused on whether changing the default SSH port serves as an improvement for one’s security setup.

SSH, or Secure Shell, is a protocol utilized by network administrators in managing systems and applications remotely. This allows quick control over servers, enabling the- execution of commands from a considerable distance.

Does Changing SSH Port Improve Security?

To boil down this argument into simple terms – yes, switching your SSH port can significantly improve your security, but not always. It’s analogous to shifting your home’s front door around. While it might protect you from door-to-door salesmen, it won’t keep out a determined thief who can discover where your new front door is. It isn’t a silver bullet against threats but another layer to your defense strategy.

Reduced visibility

If you change the SSH login from the standard port 22 to another value, you essentially hide the “entrance” to your server from prying eyes prowling port 22 specifically. It effectively reduces your visibility from automated scripts (bots) that generally target the default ports.

# Edit the sshd_config file
nano /etc/ssh/sshd_config

# Find and change the line with Port 22
Port 5555

Security through obscurity

The change in port number introduces a concept called ‘security through obscurity’. Though this idea has received its fair share of critique for being ineffective in a standalone sense, considering it as an extra layer of protection alongside more robust security processes is effective in some circumstances.

Frees up resources

A lesser-known benefit of this strategy is that it improves the economy of resources. Constant attacks and pings on the default SSH port can consume network processing power and bandwidth.

But remember, while changing the SSH port may augment security enhancements, it shouldn’t replace other, more substantive forms of protection.

It’s important to consider additional improvements to your SSH security such as:

• Using key based authentication instead of passwords

# generate a new key pair
ssh-keygen 

# copy your public key to the server
ssh-copy-id -i ~/.ssh/id_rsa.pub user@hostname

• Implementing two-factor authentication
• Limiting the IP addresses that can access the SSH server

# Add in your server's sshd_config file
AllowUsers *@IPaddress1, *@IPaddress2 

• Eliminating root logins

# Change in sshd_config file
PermitRootLogin no 

Moreover, maintaining updated software intricately tied to the SSH protocol should always be a priority.

See also

NetworkingProtocol

·March 24, 2023·25 min read

What Happens If You Disable Arp

A Note on Changing Ports

Remember, if you plan on changing your SSH port, try to stick to ports higher than 1024, and also avoid using other ports which may be needed by specific services(this will vary depending on your individual server setup). There’s also a convenience factor to consider; you’ll need to inform the port number each time you log in, since it’s no longer on the default.

In essence, changing your SSH port is but a single piece in the vast puzzle that is cybersecurity. It may hardly stop a dedicated attacker, but could serve as a deterrent to script-driven automated attacks and free up system resources. Remember: every layer of insulation counts when building a fortress. Of course, along with this practice, it’s crucial to maintain regular updates, implement reliable multiple-factor authentication methods, and carry out regular backups among other security practices.While considering improving Secure Shell Protocol (SSH) security settings, changing the SSH Port is one tactic among many that can reinforce a security implementation. However, its usefulness in significantly amplifying your SSH security should be thoroughly considered along with actionable strategies.

Firstly, changing your default SSH port from 22 to a non-standard port is indeed a strategy that offers a certain level of protection-specifically against automated attacks or scripts that scout for port 22 being open. However, it must be noted that this method primarily serves to obscure your server rather than provide substantial security reinforcement-it’s akin to “security through obscurity.” This means that while scripts and bots are less likely to find your SSH service, anyone determined enough will eventually locate it.

In coding language, if you want to change the standard SSH port you would do something like:

# Open up the configuration file for SSH
sudo nano /etc/ssh/sshd_config

# Find the line that says "Port 22"
# Change this to any number between 1024-49151, as these are unassigned ports.
Port 30000

# Save and exit the file
# Restart the SSH service for changes to take effect
sudo systemctl restart ssh

The preceding block of code opens SSH configuration settings, changes the SSH listening port to 30000, save your change, and restarts the SSH service.

However, proper SSH protection requires more robust security measures. Here are three additional strategies that could be implemented in an SSH security policy to substantially boost defense:

Ssh Key Authentication:

You’d do well to leverage SSH keys-a type of asymmetric cryptographic protocol. The advantage of SSH keys over traditional passwords is they provide a way to authoratively verify identities without relying on less secure password mechanisms.

For instance, creating an SSH key pair would look something like:

# Create a new private/public key pair
ssh-keygen -t rsa

# Don't add a passphrase, simply press "Enter"

# Now move the public key to your server
ssh-copy-id your_server_user@your_server_ip

This block of code generates a unique SSH key pair, copying your public key to the server for further user authentication.

Enable Two-Factor Authentication:

Setting up a two-factor authentication process implies setting up an additional layer of security whereby users are required to verify their identities twice before gaining server access. Google Authenticator is a popular choice for achieving this.

Limit Ssh Login Attempts:

Limiting the number of SSH login attempts effectively reduces the probability of successful brute force attacks. Tools for limiting SSH login attempts include ‘fail2ban’ and ‘DenyHost.’

Remember, while the act of changing the SSH port may offer some security advantages, treating it as a holistic protection could lead to a false sense of safety. I strongly recommend implementing multiple defensive layers-including, but not limited to altering the SSH port-as part of a comprehensive security setup.

Most importantly, always stay informed about your system’s ongoing security status, consistently audit your logs, rapidly respond to breaches, and frequently update your security knowledge because, in today’s digital age, cyberdefense isn’t a one-off installation-it’s a continual process.

Reference:
• Change the SSH Port in Linux
• What is SSH Protocol

Scaling the heights of data transfer protection requires advanced techniques, one of which is the utilization of encrypted channels. SSH (Secure Shell), a vital protocol for secure system administration and file transfers, has several security tweaks. The question here centers on whether changing the SSH default port 22 improves security. I’ll touch on this while also providing insights into encoding techniques used for enhancing data transfer protection.

Changing SSH Default Port

Is there a genuine advantage to switching your SSH terminal from port 22 to a non-standard one? It’s not an all-saving hack but it does offer deceptive security by reducing visibility and exposure to automated attacks.

Here’s how:

• A significant proportion of hacking attempts are random scans looking for open port 22 – the default SSH port.
• Shifting to a non-standard port effectively sidesteps these automated attacks.
• The attacker now needs to perform a full port scan, which significantly increases their chances of detection.

Changing SSH ports is as straightforward as editing the configuration file ‘

/etc/ssh/sshd_config

‘ and setting up the ‘Port’ directive to the desired number followed by restarting the SSH server. Here’s an example:

# /etc/ssh/sshd_config
Port 2222

# restart ssh service
service sshd restart

Note that the port number chosen must abide by the UNIX standards and avoid lower-numbered ones typically reserved for well-known services.

Enhancing Security through Encoded Tunnels

If you thought changing the SSH port was the limit of your options, welcome to the world of tunneling SSH connections in conjuncture with various encoding techniques for more secure data transmission.

SSH tunneling essentially encrypts your data before transmission and then decrypts it upon receipt. Three types of tunneled SSH connections exist: local, remote, and dynamic. Utilizing them diversifies your protection methodology and offers more robust security.

No better way to secure these tunnels than with SSL (Secure Sockets Layer) certificate files, making OpenSSL library a respected option among developers. OpenSSL provides a rich toolkit for SSL and TLS protocols, and a collection of encryption algorithms. Another benefit of SSL is that the receiving end needs to trust the certificate. Without trust, data transmission won’t proceed – an additional layer of security.

Here’s a code sample of executing a secure shell command using OpenSSL:

// Include OpenSSL header files
#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>

int main(int arc, char *argv[])
{
    ...
    // Create a new SSL_CTX object called 'ctx'
    SSL_CTX *ctx;
    ctx = SSL_CTX_new(SSLv23_client_method());
    
    // Configure the SSL_CTX object
    SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2);
     ...
}

In this instance, we create an SSL context, configure it, and will eventually use it to establish an SSL connection to encrypt data before sending via SSH.

Using SCP and SFTP for Secure File Transfers

Another important method of upgrading your secure data transfer is considering SCP (Secure Copy Protocol) and SFTP (SSH File Transfer Protocol), both of which run over SSH and hence inherit its security mechanisms.

So, does changing SSH port improve security? Yes, but merely as a first line of defense. An integrated approach that includes SSL secured SSH tunnels, encoded data transfers, and the switch to secure file transfer protocols such as SCP or SFTP provides a safer, more robust solution.

Sure! Shifting the Secure Shell (SSH) port from its default port (22) is commonly recommended as a measure to amplify security. However, this technique has sparked debates among experts about its effectiveness. Though changing the SSH port can reduce noise from automated attacks targeting the default port, it does not fundamentally enhance your security posture against focused attacks.

This question compels us to explore other effective measures that, when implemented alongside shifting the SSH port, amplify security significantly. These steps are quite crucial, and they set an agreed standard of what secure systems should look like.

Enable Key-Based Authentication

Key-based authentication is inherently more secure than password-based authentication for several reasons:

* There’s greater entropy in key files making them harder to crack.
* Password cracking tools are ineffective against key files.

Implementing key-based authentication involves generating a private and public SSH key pair, then adding the public key to the server. Any SSH client must have the private key to establish a connection. Here’s how you enable key-based authentication:

# Generate ssh key pair
ssh-keygen

# Copy public key to server
ssh-copy-id user@your.server.ip

Remember to disable password authentication once key-based authentication is enabled.

Limit User Access Control

Applying the principle of least privilege will significant improve the security of your system. By restricting the users who can log into the system, we mitigate the risk of compromising those accounts:

# Open SSH configuration file
sudo nano /etc/ssh/sshd_config

# Add limitation rules
AllowUsers username1 username2
DenyUsers username3 username4

After adding these rules, restart the SSH service for the changes to take effect.

Implementing Two-Factor Authentication (2FA)

Two-factor authentication means that even if a malicious actor gains access to your password or key files, they still cannot breach your server without physical access to your second form. This layer of protection further cements your defence.

Here are the basics for using Google Authenticator to setup 2FA on SSH login:

# Install Google Authenticator
sudo apt-get install libpam-google-authenticator

# Update SSH configuration file
sudo nano /etc/pam.d/sshd
auth required pam_google_authenticator.so

Afterwards, run google-authenticator to generate your secret key, verification code, and emergency scratch codes.

Install A Fail2Ban Service

Fail2ban is a daemon that monitors system logs for signs of automated attacks. You can configure it to temporarily or permanently ban offending IP addresses based on custom offences count. It’s a highly recommended tool to complement SSH security.

# Install fail2ban
sudo apt-get install fail2ban

# Start the service
sudo systemctl start fail2ban

It is prudent to fine tune Fail2Ban according to your system’s needs.

# Change the SSH port in sshd_config file
sudo nano /etc/ssh/sshd_config
# Find the line with #Port 22, remove the hash and change 22 to your chosen port number
Port 2222
# Save the changes then restart the SSH service
sudo service ssh restart