iptunnel_pmtud_build_icmp(9)

okay bestie, welcome to the iptunnel_pmtud_build_icmp(9) page from the Kernel API Manual 💅 this one is short, sweet, and very “kernel girlie knows exactly what she’s doing” ✨

🎀 NAME 🎀

iptunnel_pmtud_build_icmp — Build ICMP error message for PMTUD 💖

🌸 SYNOPSIS 🌸

int iptunnel_pmtud_build_icmp (struct sk_buff *skb , int mtu );

🦋 ARGUMENTS 🦋

• skb — the original packet with L2 header, no cap 🫶
• mtu — the MTU value for the ICMP error ⭐

💜 RETURN 💜

On success you get the length 🔥 and if the message couldn’t be built, you get a negative error code 😭 periodt.

🌈 SEE ALSO 🌈

The SEE ALSO squad, hanging around the kernel file ./net/ipv4/ip_tunnel_core.c 👀

• iptunnel_pmtud_check_icmp(9)
• iptunnel_pmtud_build_icmpv6(9)
• iptunnel_pmtud_check_icmpv6(9)
• skb_tunnel_check_pmtu(9)

okay that’s the whole vibe 💫 huge shoutout to the source path ./net/ipv4 and the date October 2026 — bestie, this page is giving concise kernel icon energy 👑🎀