# MODBUS/TCP Security (over TLS)

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-security-over-tls/37738>\
**Category:** General Discussion\
**Created:** [August 14, 2020, 5:07pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-security-over-tls/37738 "2020-08-14T17:07:32Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [August 14, 2020, 5:20pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-security-over-tls/37738/6 "2020-08-14T17:20:04Z")

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It’s a little different, because there’s only 1 certificate for all the outgoing OPC UA connections.

The Modbus TLS spec embeds a client-specified (!!) operator role in each client certificate, which means not only do you need one per connection, you can’t sensibly use self-signed certificates, you have to deal with having a CA-signed and issued certificate per connection from a CA that the Modbus TLS server trusts.

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