UDP 7
Synopsis
- UDP port 7 is used by the Echo Protocol (RFC 862).
- Unix/Linux systems provide it via inetd/xinetd (e.g., the xinetd “echo” service on Debian/Red Hat) and BusyBox inetd on embedded devices when enabled.
- Microsoft Windows offered it via “Simple TCP/IP Services (Echo)” on versions like Windows Server 2003/2008 (optional feature).
- Cisco IOS supports it through the “service udp-small-servers” feature, which enables the Echo service on UDP/7 for diagnostics.
- Juniper Junos includes a predefined “junos-echo” application/service (UDP/7) that can be allowed in security policies.
- BSD variants (e.g., FreeBSD/OpenBSD) include echo/udp in inetd, typically disabled by default.
- Security: UDP/7 has been abused in reflection DDoS (e.g., Fraggle) and echo–chargen loop attacks, so vendors commonly ship it disabled.
Observed activity
Last 30 days
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