Calculate available UDP port range and usable ports after reserved and ephemeral ranges.
UDP shares the same 16-bit port namespace as TCP (0–65535), with ports 0–1023 reserved as well-known ports requiring elevated privilege to bind on most systems, and this calculator lets you additionally exclude any organization-specific reserved ranges to find truly available ports for dynamic allocation. Each UDP socket also carries its own send/receive buffer allocation (controlled by SO_RCVBUF/SO_SNDBUF, defaulting from net.core.rmem_default/wmem_default), so total kernel memory committed to UDP scales with both port usage and per-socket buffer size.
Available UDP ports
available = 65535 − well_known(1024) − reserved
No — despite both using 16-bit port numbers, UDP and TCP maintain independent port tables in the kernel, so binding UDP port 8080 does not conflict with a process listening on TCP port 8080. This calculator's range excludes well-known ports by convention, not because of a shared-namespace conflict.
`sysctl net.core.rmem_default` and `sysctl net.core.wmem_default` show the default receive/send buffer sizes applied to new sockets that don't explicitly call setsockopt(SO_RCVBUF/SO_SNDBUF).
Bursty UDP traffic (e.g. syslog floods, high-rate telemetry, VoIP/RTP streams) can overflow small receive buffers before the application reads them, causing silent packet drops — increasing SO_RCVBUF (up to net.core.rmem_max) gives the kernel more room to queue incoming datagrams during bursts.