# Wago CC100 Modbus TCP Firewall rule

**URL:** <https://www.wago.community/t/wago-cc100-modbus-tcp-firewall-rule/1934>\
**Category:** Hardware and Linux\
**Created:** [June 8, 2025, 1:19pm UTC](https://www.wago.community/t/wago-cc100-modbus-tcp-firewall-rule/1934 "2025-06-08T13:19:18Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rgillard](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@rgillard](https://www.wago.community/u/rgillard)\
**Post date:** [June 8, 2025, 1:19pm UTC](https://www.wago.community/t/wago-cc100-modbus-tcp-firewall-rule/1934/1 "2025-06-08T13:19:18Z")

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I’ve just started playing with the CC100. I have a simple Modbus TCP application up and running. The problem is when I enable the firewall port 502 is blocked. I can’t see any options for this in WBM. Not being familiar with the firewall system, I’m struggling a bit with setting up via console as well. I’m running firmware 04.06.03. It seems strange that there’s not a standard option for allowing Modbus TCP, or am I missing something?

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**Author:** ![WagoTorgeir](https://sea2.discourse-cdn.com/flex016/user_avatar/www.wago.community/wagotorgeir/32/78_2.png) [@WagoTorgeir](https://www.wago.community/u/WagoTorgeir)\
**Post date:** [June 8, 2025, 3:05pm UTC](https://www.wago.community/t/wago-cc100-modbus-tcp-firewall-rule/1934/2 "2025-06-08T15:05:45Z")

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When the CC100 firewall is activated (via WBM =\> Security =\> Firewall…), all unlisted ports are blocked, including the Modbus port (502). To remove this blockage, the relevant/desired port must be specified via an associated “User Filter”, i.e.:  
[https://wago.sharepoint.com/:i:/s/O\_36\_Customer\_Downloads/EZxdn7NgX01JtSV85Qz-iCYBMvVU8IqNmJacVawYBXfONw?e=cRD0Xi](https://wago.sharepoint.com/:i:/s/O_36_Customer_Downloads/EZxdn7NgX01JtSV85Qz-iCYBMvVU8IqNmJacVawYBXfONw?e=cRD0Xi)

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**Author:** ![rgillard](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@rgillard](https://www.wago.community/u/rgillard)\
**Post date:** [June 8, 2025, 5:07pm UTC](https://www.wago.community/t/wago-cc100-modbus-tcp-firewall-rule/1934/3 "2025-06-08T17:07:22Z")

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Thank you so much! Not sure why I didn’t spot that option in WBM, I thought I had looked everywhere.