How to enable IPv6 support
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Historical ScreenOS 6.2 procedure for enabling IPv6.
Legacy / version-specific guidance
This page applies to ScreenOS/NetScreen. Current Junos OS configures IPv6 under the family inet6 hierarchy rather than through the ScreenOS environment variable below.
Validation status
Reviewed during the Tech-Wiki Wave 3 migration on 27 September 2026. The historical procedure is retained for engineers supporting older estates, but is not presented as the default approach for a new deployment.
Legacy ScreenOS reboot procedure
Do not use the ScreenOS set envar ipv6=yes workflow on an SRX/Junos device.
Historical procedure
As of ScreenOS 6.2 IPv6 is supported in ScreenOS. It is however disabled by default.
In order to enable IPv6, the environment variable needs to set by the administrator.
set envar ipv6=yes
The firewall needs to then be is rebooted, at which point IPv6 will be enabled. To check this has been enabled run the command
get envar
You should see the following:
netscreen-> get envar ipv6=yes
To remove this behaviour the following command needs to be set by the root administrator:
unset envar ipv6=yes
Once again the firewall needs to be rebooted to change the firewall back to the default behavior.