WINDOWS

1. Open the downloaded omniarc-ca.cer and choose Install Certificate.
2. Choose Local Machine (every account on this computer; Windows asks for an administrator) or Current User.
3. Choose Place all certificates in the following store, Browse, Trusted Root Certification Authorities, then Next and Finish.
4. Close and open the browser again.

On the computer OMNIARC runs on, the installer did this already. Firefox uses Windows' certificates when its setting "security.enterprise_roots.enabled" is on (the default on Windows).

ANDROID

1. Open Settings, then Security (or Security and privacy), then Encryption & credentials (on some phones: More security settings).
2. Choose Install a certificate, then CA certificate, then Install anyway.
3. Pick omniarc-ca.cer from Downloads.

Some apps trust only the certificates the phone came with; those connect to OMNIARC with their own settings (TAK apps with OMNIARC's connection package).

IPHONE AND IPAD

1. Open this page in Safari and download the profile; choose Allow.
2. Open Settings: Profile Downloaded is at the top. Choose it, then Install (it says Not Verified: compare the fingerprint above).
3. Then Settings, General, About, Certificate Trust Settings, and switch on full trust for the OMNIARC certificate.

MAC

1. Open the downloaded omniarc-ca.cer: Keychain Access opens. Add it to the System keychain.
2. Open the certificate in Keychain Access, open Trust, and set When using this certificate to Always Trust.

LINUX

Debian and Ubuntu: copy it to /usr/local/share/ca-certificates/omniarc-ca.crt and run sudo update-ca-certificates. Fedora and Red Hat: copy it to /etc/pki/ca-trust/source/anchors/ and run sudo update-ca-trust.