ip6_tnl_siocdevprivate(9)

💅 ip6_tnl_siocdevprivate(9) — the Kernel API Manual page you didn't know you needed 🎀

okay so bestie, welcome to the Kernel API Manual, section 9, and today's main character is ip6_tnl_siocdevprivate ✨ she configures ipv6 tunnels from userspace and she is, honestly, kind of iconic for it 🌈

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🌸 NAME 🌸

ip6_tnl_siocdevprivate — configure ipv6 tunnels from userspace 🛠️💖

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✨ SYNOPSIS ✨

int ip6_tnl_siocdevprivate (struct net_device *dev , struct ifreq *ifr ,
void __user *data , int cmd );

like, that's the whole signature, no cap 🔥

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🦋 ARGUMENTS 🦋

• dev — the virtual device that's associated with the tunnel 👑 she's the one holding the tunnel vibes
• ifr — unused 🙈 literally just sitting there, not contributing, we still love her
• data — the parameters that got passed down from userspace 📦
• cmd — the command that's gonna be performed ⚡

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💜 DESCRIPTION 💜

so ip6_tnl_ioctl is the one doing the actual managing of IPv6 tunnels from userspace, periodt 💅

the possible commands are the following, and yes you need to know all of them 🧚:

• SIOCGETTUNNEL: get tunnel parameters for device 🔍
• SIOCADDTUNNEL: add tunnel matching given tunnel parameters ➕
• SIOCCHGTUNNEL: change tunnel parameters to those given 🔁
• SIOCDELTUNNEL: delete tunnel 🗑️

and the fallback device "ip6tnl0" — created during module initialization — can be used for creating other tunnel devices 🌱 she's giving founding mother energy, honestly obsessed 🫶

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🌟 RETURN 🌟

• 0 on success 🎉 slay
• -EFAULT if unable to copy data to or from userspace 😭 the copy failed bestie
• -EPERM if the current process hasn't CAP_NET_ADMIN set 🚫 no permission, no tunnel
• -EINVAL if the passed tunnel parameters are invalid 💀
• -EEXIST if changing a tunnel's parameters would cause a conflict ⚔️
• -ENODEV if attempting to change or delete a nonexisting device 👻 she's not there, girl

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🎀 SEE ALSO 🎀

go look at the Kernel file ./net/ipv6/ip6_tunnel.c 💖 and then 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_change_mtu(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)

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and that's the page!! 💫 this one's from ./net/ipv6, dated October 2026, and it's the ip6_tnl_siocdevprivate(9) moment — mwah, go configure some tunnels, ily 🍓💅👑