Firewalls for Industrial Networks
(Existing Customers Only)
Serial Encryptor 
     - Advanced Encryption Standard
     - Hash Authentication
     - Supports Modbus/DNP3 links
     - RS-485/422/232

PortBloque S
Modbus Serial Firewall
     - Modbus deep packet inspection
     - Modbus RTU/ASCII
     - RS-485/422/232 interface
     - Adds Modbus security to an existing firewall

PortBloque E
The Ethernet firewall that's Modbus dedicated.
$495 USD
Made in California

Protects Modbus systems from Internet threats
PortBloque™ ("port block") E is a Modbus Ethernet firewall to protect serial control devices from unwanted Internet traffic. It performs deep packet inspection (DPI) on Modbus traffic to ensure that systems receive only the commands required for normal operations and not accidental or unauthorized commands that could lead to harmful consequences.
Two Firewalls in One
Evades Port Scanning
Converts Ethernet to Serial
PortBloque E is really two firewalls in one. It performs standard firewall functions plus advanced Modbus filtering. System and traffic activity can be sent to a syslog server for later analysis.
Stealth mode makes Modbus ports invisible from sniffing. Any probing is completely ignored, as if the packet were lost in space. 
The purpose-built firewall positions at the entry point to serial devices and supports an RS-232, RS-422, or RS-485 connection. It automatically converts Modbus TCP/IP to Modbus RTU/ASCII. No need to change the Modbus network or applications. 
Filters anything and everything  
Modbus filtering is easy! Simply enter the Modbus device IDs you want to make available. Then select the types of Modbus function codes you want those devices to receive. These can include user-defined function codes, like that circled in the screen image. 
By defining register and range values, you can prevent the control device from being put into an undesired or unstable mode. You can also control the amount of time to wait before a command can be repeated.

Key features
PortBloque E
Firewall Rules
  • Modbus deep packet inspection (DPI):
    • Device IDs: single or group, incl. broadcast ID 
    • Function codes:  1-8, 11,12, 15-17, 20-24, 43;
                                  four user-defined codes
    • Registers 
    • Values 
  • Safeguard time between repeated commands
  • Access control list
  • Stealth mode (makes Modbus ports invisible)
  • Source IP, Protocol, and Port 
Ethernet-to-Serial Conversion Built-in

  • Ethernet
    • Modbus TCP/UDP 
    • Modbus RTU over TCP/UDP 
    • Modbus ASCII over TCP/UDP 
  • Serial
    • Modbus RTU/ASCII 

  • RS-485 2-wire, RS-422 4-wire, RS-232
  • Slave: 10-pin terminal block
  • Slave and Mgmt: DB9
  • Host: RJ45 Ethernet (10/100BaseT)

Web Interface 
  • Easy click configuration 
  • Login-secure levels: Superuser, User 
  • Dashboard for at-a-glance firewall statistics 
  • Syslog  
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Order Information

          PortBloque E     $495.00 USD
PortBloque E is available for purchase using PayPal (you do NOT need a PayPal account). Select the quantity from the dropdown and click on the 'Buy Now' button. 

Orders ship within one week via UPS Ground.
PortBloque E (quantity+shipping):
         Please use the online Order Request form.
          Please use the online Order Request form.
Get in touch!
Please contact us with your questions.