All news with #soft-unicast tag
Wed, October 29, 2025
How We Escaped the Linux Networking Stack for Soft-Unicast
🐟 Cloudflare describes building "fish" (SLATFATF), a service to egress packets using soft-unicast address space and the challenges encountered with the Linux networking stack. They found that conntrack and Netfilter interactions can silently rewrite source ports and break connections, so they evaluated several approaches including Netlink manipulation, TCP_FASTOPEN_CONNECT sockets, and routing fixes. Ultimately they preferred terminating and proxying TCP locally to avoid fragile kernel workarounds, after testing that disabling early demux produced only modest CPU effects.