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Router Security Configuration Guide UNCLASSIFIED 232 UNCLASSIFIED Version 1.0g OSPF Open Shortest Path First – an IP routing protocol that uses a link-state distance metric.  OSPF is standardized in RFC 2328.  (See also RIP) Proxy Any application that acts as an intermediary in the network exchanges between two applications or services.  Proxy applications are often employed to moderate exchanges through a firewall. Proxy-ARP A facility offered by some routers where a router responds to ARP queries from a connected LAN on behalf of hosts on other LANs.  Rarely used. RADIUS The Remote Authentication Dial-In User Service (RADIUS) is specified by the IETF RFC 2058.  Using RADIUS, access servers can communicate with a central server to authenticate, authorize, and audit user activities. RFC Request For Comments – a document describing an Internet standard, proposed standard, or information related to or supports a standard.  (See IETF) RIP Router Information Protocol – a simple inter-gateway routing protocol that uses hop count as its distance metric.   RIP is standardized by RFCs 1088, 1388, and 1723.  (See also OSPF) RMON Remote MONitoring – facilities for remote performance and traffic monitoring of network devices, based on SNMP.    Routing Direction and management of paths through a multi-segment network. (See also RIP, OSPF) RSVP Resource reSerVation Protocol – fairly new standard protocol for requesting quality-of-service guarantees in IP networks.  RSVP is standardized in RFC 2205. SMTP Simple Mail Transfer Protocol – a TCP-based protocol for sending and relaying e-mail messages.  SMTP is standardized in RFC 821. SNMP Simple Network Management Protocol – datagram protocol used for monitor ing and configuring network devices.   SNMP uses UDP ports 161 and 162.  SNMP is standardized in RFC 1157 and other RFCs.  (See also RMON); Syslog A very simple UDP-based protocol used for logging by Unix systems and Cisco routers.  Syslog usually employs UDP port 514.