BSD syscall#522
svc · unix #522
necp_session_open
Opens a privileged NECP session for installing system-wide policies and inspecting client state.
Prototype
int necp_session_open(int flags);Returns: int
Arguments
| Name | Type | Dir | Description |
|---|---|---|---|
| flags | int | - |
Version history
| XNU tag | macOS | # |
|---|---|---|
| xnu-4570.1.46 | macOS 10.13 High Sierra | 522 |
| xnu-4903.221.2 | macOS 10.14 Mojave | 522 |
| xnu-6153.11.26 | macOS 10.15 Catalina | 522 |
| xnu-7195.50.7.100.1 | macOS 11.0 Big Sur | 522 |
| xnu-8019.41.5 | macOS 12.0 Monterey | 522 |
| xnu-8792.41.9 | macOS 13.0 Ventura | 522 |
| xnu-10002.1.13 | macOS 14.0 Sonoma | 522 |
| xnu-11215.1.10 | macOS 15.0 Sequoia | 522 |
| xnu-11417.101.15 | macOS 15.4 Sequoia | 522 |
| xnu-12377.1.9 | macOS 26.0 Tahoe | 522 |
| xnu-10002.41.9 | — | 522 |
| xnu-10002.61.3 | — | 522 |
| xnu-10002.81.5 | — | 522 |
| xnu-10063.101.15 | — | 522 |
| xnu-10063.121.3 | — | 522 |
| xnu-10063.141.1 | — | 522 |
| xnu-11215.41.3 | — | 522 |
| xnu-11215.61.5 | — | 522 |
| xnu-11215.81.4 | — | 522 |
| xnu-11417.121.6 | — | 522 |
| xnu-11417.140.69 | — | 522 |
| xnu-12377.101.15 | — | 522 |
| xnu-12377.41.6 | — | 522 |
| xnu-12377.61.12 | — | 522 |
| xnu-12377.81.4 | — | 522 |
| xnu-4570.20.62 | — | 522 |
| xnu-4570.31.3 | — | 522 |
| xnu-4570.41.2 | — | 522 |
| xnu-4570.51.1 | — | 522 |
| xnu-4570.61.1 | — | 522 |
| xnu-4570.71.2 | — | 522 |
| xnu-4903.231.4 | — | 522 |
| xnu-4903.241.1 | — | 522 |
| xnu-4903.270.47 | — | 522 |
| xnu-6153.101.6 | — | 522 |
| xnu-6153.121.1 | — | 522 |
| xnu-6153.141.1 | — | 522 |
| xnu-6153.41.3 | — | 522 |
| xnu-6153.61.1 | — | 522 |
| xnu-6153.81.5 | — | 522 |
| xnu-7195.101.1 | — | 522 |
| xnu-7195.121.3 | — | 522 |
| xnu-7195.141.2 | — | 522 |
| xnu-7195.60.75 | — | 522 |
| xnu-7195.81.3 | — | 522 |
| xnu-8019.61.5 | — | 522 |
| xnu-8019.80.24 | — | 522 |
| xnu-8020.101.4 | — | 522 |
| xnu-8020.121.3 | — | 522 |
| xnu-8020.140.41 | — | 522 |
| xnu-8792.61.2 | — | 522 |
| xnu-8792.81.2 | — | 522 |
| xnu-8796.101.5 | — | 522 |
| xnu-8796.121.2 | — | 522 |
| xnu-8796.141.3 | — | 522 |
Notes
Distinct from necp_open: sessions are the API used by nehelper to manage the global policy table — VPN routing rules, content-filter ordering, per-app traffic rules from a Configuration Profile. Requires the com.apple.private.necp.match-policy or .session entitlement. The returned fd is fed into necp_session_action for every subsequent modification.
Detection
Only Apple system services should invoke this. ES exposes no event, but the syscall pid can be cross-checked against /System/Library/Frameworks/NetworkExtension.framework/XPCServices via process auditing.
Related APIs
necp_opennecp_session_actionnecp_match_policynecp_client_action