Monitor Latency with SmokePing on Ubuntu 20.04

Introduction

At a high level, SmokePing checks network latency. Setting up SmokePing in multiple Vultr locations can help address network issues with cloud compute services before they happen. SmokePing emulates customer connections and can show external problems and network issues that might not be visible internally.

Prerequisites

A DNS domain. This guide uses smokeping.example.com.
A Vultr cloud server. This guide uses Ubuntu 20.04.

1. Launch A New Vultr Cloud Compute Instance

SmokePing has the ability to monitor in an active passive format. This allows views from different locations. The configuration and steps below depict a single location and are meant to be used as a starting point for developing a more robust monitoring platform. The first location should be where your user base is more heavily concentrated or what suits your use-case. This guide uses a Ubuntu 20.04 x64 server with 25GB SSD and IPv4 connectivity. Ensure that HTTP and HTTPS traffic can pass through the firewall to the instance.

2. Create a DNS Record

Create an A record that points your domain name to the IP address of your cloud compute instance.

3. Install the Required Libraries

SmokePing requires a web server, and this guide uses Nginx. SmokePing also requires Common Gateway Interface (CGI) scripting. The guide implements fcgiwrap. To install SmokePing and fcgiwrap, as well as update the server, run these commands:

# apt update -y

# apt dist-upgrade -y

# apt install nginx -y

# apt install fcgiwrap -y

# apt install smokeping -y

When prompted by the Postfix installer, choose Internet Site. When prompted for mail name, leave the name of the server. Leave the mail for postmaster and root blank.

4. Configure fcgiwrap

The CGI wrapper needs to interact with Nginx. Configure Nginx with the default configuration.

# cp /usr/share/doc/fcgiwrap/examples/nginx.conf /etc/nginx/fcgiwrap.conf

5. Configure Nginx

As a best practice for Nginx, delete the default web site.
```
# sudo rm /etc/nginx/sites-enabled/default
```
Create a no-site web site, which answers any requests destined for the host that do not contain the correct DNS name.
```
# sudo nano /etc/nginx/sites-available/no-site
```

Paste the following configuration into the file.

server {

    listen 80 default_server deferred;

    listen [::]:80 default_server deferred;

    server_name _;



    # Return 444 (No Response)

    return 444;

}

Save the file and exit.

Create a site configuration for SmokePing.

# sudo nano /etc/nginx/sites-available/smokeping

Paste the following configuration in the file. Change the server_name directive to match your DNS record name.

server {

    listen 80;

    listen [::]:80;

    server_name smokeping.example.com;



    location = /smokeping/smokeping.cgi {

            fastcgi_intercept_errors on;



            fastcgi_param   SCRIPT_FILENAME         /usr/lib/cgi-bin/smokeping.cgi;

            fastcgi_param   QUERY_STRING            $query_string;

            fastcgi_param   REQUEST_METHOD          $request_method;

            fastcgi_param   CONTENT_TYPE            $content_type;

            fastcgi_param   CONTENT_LENGTH          $content_length;

            fastcgi_param   REQUEST_URI             $request_uri;

            fastcgi_param   DOCUMENT_URI            $document_uri;

            fastcgi_param   DOCUMENT_ROOT           $document_root;

            fastcgi_param   SERVER_PROTOCOL         $server_protocol;

            fastcgi_param   GATEWAY_INTERFACE       CGI/1.1;

            fastcgi_param   SERVER_SOFTWARE         nginx/$nginx_version;

            fastcgi_param   REMOTE_ADDR             $remote_addr;

            fastcgi_param   REMOTE_PORT             $remote_port;

            fastcgi_param   SERVER_ADDR             $server_addr;

            fastcgi_param   SERVER_PORT             $server_port;

            fastcgi_param   SERVER_NAME             $server_name;

            fastcgi_param   HTTPS                   $https if_not_empty;



            fastcgi_pass unix:/var/run/fcgiwrap.socket;

    }



    location ^~ /smokeping/ {

            alias /usr/share/smokeping/www/;

            index smokeping.cgi;

            gzip off;

    }



    location / {

            return 301 http://$server_name/smokeping/smokeping.cgi;

    }

}

Save the file and exit.

Link the two configuration files to the Nginx configuration.

# ln -s /etc/nginx/sites-available/smokeping /etc/nginx/sites-enabled/smokeping

# ln -s /etc/nginx/sites-available/no-site /etc/nginx/sites-enabled/no-site

Restart the web server.
```
# sudo service nginx restart
```
Nginx should restart without any errors. If it returns any errors, check the syntax by running:
```
# sudo nginx -t
```

Enable HTTPS with LetsEncrypt. Replace the example values with your DNS name and email address.

# sudo apt install -y certbot python3-certbot-nginx

# sudo certbot --non-interactive --redirect --agree-tos --nginx -d smokeping.example.com -m admin@example.com

With this configuration completed, your web server is available with HTTPS.

6. Configure SmokePing

The final step is configuring SmokePing to use HTTPS and to ping clients.

Edit the General configuration
```
# sudo nano /etc/smokeping/config.d/General
```
Change the following values:
- owner - Set this to your name.
- contact - Set this to your email.
- mailhost - Set this to localhost.
- cgiurl - Set this to https://smokeping.example.com/smokeping/smokeping.cgi and change smokeping.example.com to your DNS record.
Save the file and exit.

Edit the Targets and add monitored hosts:

# sudo nano /etc/smokeping/config.d/Targets

Append the following to the end of the file (as well as any extra hosts):

+ websites

menu = Website Monitoring

title = Website Monitoring



++ example1

probe = FPing

host = one.example.com

title = Example One



++ example2

probe = FPing

host = two.example.com

title = Example Two

Save the file and exit.
Restart the SmokePing daemon.
```
# sudo service smokeping restart
```

7. Configure Postfix to use SendGrid

By default, Postfix attempts to send mail directly, which is insecure. Follow these steps to configure SendGrid as the mail relay.

Sign up for a free SendGrid account.
Log in to the SendGrid dashboard.
Navigate to Settings -> API Keys.
Click "Create API Key" in the upper right.
Name the API Key and choose "Restricted Access".
- Scroll down to "Mail Send" and click the dot to the far right.
Click "Create and View".

Make a note of your API key, it will be shown one time.

Edit the main Postfix configuration file.
```
# sudo nano /etc/postfix/main.cf 
```

Add these lines to the end.

smtp_sasl_auth_enable = yes

smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

smtp_sasl_security_options = noanonymous

smtp_sasl_tls_security_options = noanonymous

smtp_tls_security_level = encrypt

header_size_limit = 4096000

relayhost = [smtp.sendgrid.net]:587

Save the configuration.
Create a password file.
```
# sudo nano /etc/postfix/sasl_passwd
```
Add the following line. Replace API-KEY-GOES-HERE with your API key.
```
[smtp.sendgrid.net]:587 apikey:API-KEY-GOES-HERE
```
Save and exit the file.

Change the permissions, encrypt the file, and restart Postfix.

# sudo chmod 600 /etc/postfix/sasl_passwd

# sudo postmap /etc/postfix/sasl_passwd

# sudo systemctl restart postfix

Conclusion

You can use SmokePing to graph latency between your servers running in different Vultr locations and configure it to send email alerts during outages. SmokePing gives you a better overview of your architecture from various points around the world.

References

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