NG_EIFACE(4)

💖 NG_EIFACE 💖

okay bestie, so this is a Kernel Interfaces Manual page for ng_eiface, section 4. yes we're doing kernel stuff today and yes you're gonna slay it. 🎀

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✨ NAME ✨

ng_eiface — generic Ethernet interface netgraph node type

like. that's the whole vibe. a netgraph node that is an Ethernet interface. iconic behavior honestly. 🦋

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🌸 SYNOPSIS 🌸

#include <netgraph/ng_eiface.h>

that's it. one include. we love a low-effort entry point. 💅

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💫 DESCRIPTION 💫

so the eiface netgraph node implements the generic Ethernet interface. the way that works is: when an eiface node gets created, a whole new interface just appears, and you can go touch it with ifconfig(8). main character entrance fr. ✨

these interfaces are named ngeth0, ngeth1, etc. — numbered, cute, orderly. 🎀

when a node is shut down, its matching interface gets removed, and that interface name goes back into the pool, available for reuse by future eiface nodes. and heads up: new nodes always take the first unused interface. no skipping, no choosing, first come first served. that's just the rules bestie. 💀

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🪝 HOOKS 🪝

an eiface node has exactly one single hook, and its name is ether. one hook. monogamous. loyal. 🫶

you should connect it to the Ethernet downstream — for example, to the ng_vlan(4) node. that's its whole social circle.

• packets transmitted via the interface flow out this hook
• packets received on the hook go to the protocol stack exactly like packets received by any real Ethernet interface

so like, it's giving real NIC, but it's a node. no cap. 🌈

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📨 CONTROL MESSAGES 📨

this node type supports the generic control messages, plus these extra ones:

• NGM_EIFACE_SET (ASCII name: set) — sets the link-level address of the interface. requires struct ether_addr as its argument. this message also has an ASCII version, called set, which instead requires an ASCII string made of 6 colon-separated hex digits. so like 00:11:22:33:44:55 energy. 💅
• NGM_EIFACE_GET_IFNAME (ASCII name: getifname) — returns the name of the associated interface, as a NULL-terminated ASCII string. yes it's null-terminated, we are not out here guessing string lengths, that's not the vibe. 🙈
• NGM_EIFACE_GET_IFADDRS — returns the list of link-level addresses associated with the node. plural addresses, so if you were expecting just one... surprise bestie. 💖

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💀 SHUTDOWN 💀

this node shuts down upon receipt of a NGM_SHUTDOWN control message. the associated interface gets removed, and its name becomes available for reuse by future eiface nodes. circle of life. 🦋

IMPORTANT WARNING — unlike most other node types, an eiface node does not go away when all hooks have been disconnected. it just... stays there. chilling. an explicit NGM_SHUTDOWN control message is required. so don't come crying to me when you unplug everything and the node is still standing there like 👑. you have to actually tell it to leave.

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👀 SEE ALSO 👀

netgraph(4), ng_ether(4), ng_iface(4), ng_vlan(4), ifconfig(8), ngctl(8)

the whole friend group. go read them too, iykyk. 📚

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📜 HISTORY 📜

the eiface node type was implemented in FreeBSD 4.6. old money. vintage. we respect the elders. ⭐

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👑 AUTHORS 👑

• the eiface node type was written by Vitaly V Belekhov
• this manual page was written by Gleb Smirnoff

absolute legends, both of them. 🫶

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okay that's the whole page bestie, you're officially an ng_eiface girlie now. this one shipped out from Debian, dated May 14, 2019, and it lives under the name NG_EIFACE(4) — go be the main character of your own network stack. mwah. 💅💖✨