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

PortBloque E
Modbus Ethernet Firewall
     - Modbus deep packet inspection
     - Modbus Ethernet to Serial Conversion

            Modbus TCP/UDP
     - RS-232/422/485 interface

PortBloque S
The serial firewall that's Modbus dedicated.
$495 USD
Made in California

Enforces safe and secure operations
PortBloque™ ("port block") S can prevent attacks on Modbus control systems.
The purpose-built firewall looks deep inside Modbus packets to ensure that systems receive only the commands required for normal operations and not accidental or unauthorized commands that could lead to harmful consequences.

Modbus security
PortBloque S peforms advanced Modbus filtering to protect serial control devices. It installs easily on RS-485, RS-422, or RS-232 networks. It can also be used in conjunction with a standard firewall to provide strong Modbus security. 
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. 

Key features
PortBloque S
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 
  • Bidirectional filtering  
Serial Protocols 
  • Modbus RTU 
  • Modbus ASCII
Data Rate 
  • 300 to 115.2K bps (async)
  • RS-485 2-wire, RS-422 4-wire, RS-232
  • Host/Slave: 10-pin terminal block
  • Host, Slave, and Mgmt: DB9
  • LAN: RJ45 Ethernet (10/100BaseT)

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

          PortBloque S     $495.00 USD
PortBloque S 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 S (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.