eth_hw_addr_random(9)

💅 eth_hw_addr_random(9) 💅

okay bestie, so this is a page from the Kernel API Manual and it's about one tiny little function that does one tiny little thing and honestly? it's kind of iconic. no cap.

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✨ NAME ✨

eth_hw_addr_random — generate a software assigned random Ethernet and set the device flag 🎀

like, it makes a random MAC and then it tells everyone about it (via a flag). main character energy fr.

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🦋 SYNOPSIS 🦋

void eth_hw_addr_random (struct net_device *dev );

that's it. that's the whole signature. void in, void out, no return value to stress about 💖

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🌸 ARGUMENTS 🌸

• dev — pointer to net_device structure. yes queen, you gotta hand over a pointer to the net_device you want to mess with 🫶

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👑 DESCRIPTION 👑

so here's the vibe check: this function generates a random Ethernet address (MAC) that's meant to be used by a net device. and then — this is the part people forget — it sets addr_assign_type so that the state can be read by sysfs and can be used by userspace.

basically:

1. random MAC gets made 🎲
2. the device gets it ✨
3. addr_assign_type gets set so sysfs can read the state 📖
4. and userspace can actually use that info 💅

the way that this is literally just "make random MAC, be transparent about it" — the honesty of it all 😭

ngl bestie, the addr_assign_type bit is the whole point. a random address with no record of why it's random is just chaos. this function is chaos with receipts 💜

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🧚 SEE ALSO 🧚

okay this is the part where the page just. keeps. going. and honestly we love a thorough girlie 🌈

it all lives in the kernel file ./include/linux/etherdevice.h, and here's the full squad:

• is_link_local_ether_addr(9)
• is_zero_ether_addr(9)
• is_multicast_ether_addr(9)
• is_local_ether_addr(9)
• is_broadcast_ether_addr(9)
• is_unicast_ether_addr(9)
• is_valid_ether_addr(9)
• eth_proto_is_802_3(9)
• eth_random_addr(9)
• eth_broadcast_addr(9)
• eth_zero_addr(9)
• eth_hw_addr_crc(9)
• ether_addr_copy(9)
• eth_hw_addr_set(9)
• eth_hw_addr_inherit(9)
• ether_addr_equal(9)
• ether_addr_equal_64bits(9)
• ether_addr_equal_unaligned(9)
• ether_addr_equal_masked(9)
• ether_addr_to_u64(9)
• u64_to_ether_addr(9)
• eth_addr_dec(9)
• eth_addr_inc(9)
• eth_addr_add(9)
• is_etherdev_addr(9)
• compare_ether_header(9)
• eth_hw_addr_gen(9)
• eth_skb_pkt_type(9)
• eth_skb_pad(9)

twenty-nine whole entries, bestie. twenty-nine. and you know every single one of them is somebody's hyperfixation 🍓

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and that's the page!! no notes, she's perfect 💅✨

sign-off time: this lil beauty lives in ./include/linux and the version on the tin says October 2026 — and the page is, of course, eth_hw_addr_random(9) 🎀🫶💖