ip6_tnl_change_mtu(9)

💅 ip6_tnl_change_mtu(9) — the kernel API manual, bestie edition 🎀

okay so you're in the Kernel API Manual (section 9, the kernel-API girlies ✨) and you found ip6_tnl_change_mtu — literally the glow-up artist for your tunnel device's MTU. no cap, this is the whole vibe:

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🌸 NAME 🌸

ip6_tnl_change_mtu — change mtu manually for tunnel device

like, you're hand-setting the MTU yourself. main character energy only 💅

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✨ SYNOPSIS ✨

int ip6_tnl_change_mtu (struct net_device *dev , int new_mtu );

that's it. that's the whole signature. she's short and she knows it 🫶

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🦋 ARGUMENTS 🦋

• dev — the virtual device associated with the tunnel. your tunnel's lil home address, basically 🏠
• new_mtu — the new mtu. yes queen, pick a number 👑

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🎀 RETURN 🎀

• 0 on success — slay, we ate, the mtu is changed ✅
• -EINVAL if mtu too small — nope, that's a no from the kernel, too tiny 🙈

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💜 SEE ALSO 💜

Kernel file ./net/ipv6/ip6_tunnel.c — the sacred text, iykyk 📖✨

and the whole friend group: ip6_tnl_lookup(9), ip6_tnl_bucket(9), ip6_tnl_link(9), ip6_tnl_unlink(9), ip6_tnl_create(9), ip6_tnl_locate(9), ip6_tnl_dev_uninit(9), ip6_tnl_parse_tlv_enc_lim(9), ip6_tnl_addr_conflict(9), ip6_tnl_xmit(9), ip6_tnl_change(9), ip6_tnl_siocdevprivate(9), ip6_tnl_dev_setup(9), ip6_tnl_dev_init_gen(9), ip6_tnl_dev_init(9), ip6_fb_tnl_dev_init(9), ip6_tunnel_init(9), ip6_tunnel_cleanup(9)

like, the entire tunnel squad, all in one place 💀🔥

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ngl bestie, if your mtu's too small you're getting -EINVAL and that's on periodt. size matters to this function, no cap 💀

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and that's the page! 🧚 source path ./net/ipv6, dated October 2026 — mwah, love u, go forth and set your MTUs responsibly 🍓💖