510

Port 510/tcp carries fcp, IANA's registered name for the FirstClass Protocol — the proprietary client-server messaging and collaboration protocol used by FirstClass groupware software; it should generally be restricted to trusted networks rather than opened broadly to the public internet, since the protocol is legacy, proprietary, and effectively unaudited today.

IANA lists port 510 as dual-registered on both TCP and UDP under the service name fcp, assignee Mike_Marshburn, with a blank Reference column — no RFC formally documents the wire protocol. The IANA description field reads simply "FirstClass Protocol," leaving implementation details outside the registry itself.

Secondary port-lookup sites (t1shopper.com, whatportis.com) consistently attribute traffic on this port to FirstClass, a client-server email, conferencing, calendaring, and directory platform originally built by SoftArc, later owned by Centrinity, and now part of Open Text Corporation. FirstClass was historically popular with schools and small/medium businesses as an all-in-one messaging system.

The nmap-services corpus records an open-frequency of about 0.0063% for 510/tcp and 0.09% for 510/udp — both low, consistent with FirstClass being a niche, aging product rather than a widely deployed modern service. No CVE specific to FirstClass or this port surfaced in an August 2026 search, and no malware/trojan verdict could be sourced from available lookups either way.

Exposure

Restricted — FirstClass servers are meant to be reachable by remote mail/conferencing clients, but the protocol is proprietary and largely unmaintained today, so direct public exposure is discouraged in favor of VPN or allowlisted access.

Prevalence

Open-frequency of roughly 0.0063% on TCP and 0.09% on UDP in the nmap-services corpus makes a responsive port 510 an uncommon sighting in modern scans [Confirmed] — this site's own tooling

Malware association

No malware or trojan association is recorded in the lookups checked as of an August 2026 search.

Vendor status

The associated FirstClass groupware platform is now a legacy product under Open Text (formerly SoftArc/Centrinity), so a live deployment today likely reflects an old install rather than active development.

IANA assignment

fcp — "FirstClass Protocol"; reference (blank — no RFC cited); assignee Mike_Marshburn; dual-registered 510/tcp + 510/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry fcp 510/tcp

Range class

well-known / system (0–1023) [Confirmed] — this site's own tooling (range: "system")

Prevalence

nmap-services open-frequency 510/tcp ≈ 0.000063 (~0.0063%); 510/udp ≈ 0.000923 (~0.09%) [Confirmed] — this site's own tooling

Related ports

510/udp (same dual IANA registration); other legacy system-port mail/collaboration services in the low system-port range

Primary use

FirstClass Protocol (fcp), a proprietary client-server messaging/collaboration protocol; no RFC defines the wire format

Other/unofficial uses

FirstClass groupware software (SoftArc → Centrinity → Open Text Corporation) for email, conferencing, calendaring, and directory services, mainly in education and small-business deployments

Security implications

no CVE specific to FirstClass or port 510 found as of an August 2026 search; malware/trojan association Unknown (available lookup pages did not return specific port-510 verdict content) [Unknown]

Typically seen on

legacy FirstClass mail/collaboration servers, historically common at schools and small/medium businesses

Analyst note

An open port 510 today most likely indicates a legacy FirstClass deployment; given the product's niche, largely unmaintained status, treat an unexpected sighting as worth verifying rather than assuming routine mail traffic.

Port 510/udp carries fcp, the FirstClass Protocol — IANA's registered name for OpenText's (formerly Centrinity's) FirstClass groupware and messaging platform — and it should be limited to trusted networks rather than exposed openly to the public internet, since the protocol is proprietary and its wire format is not publicly documented.

IANA lists the service as fcp / "FirstClass Protocol" with no RFC or specification cited in the reference column, and the assignment is dual-registered on both 510/tcp and 510/udp under assignee Mike Marshburn. Because no public protocol specification exists, independent verification of on-the-wire behavior is limited to what FirstClass client and server documentation describes.

FirstClass is the only application consistently associated with this port across port-database and reference sources. It provided email, conferencing, calendaring, and bulletin-board-style document sharing, historically deployed by schools, community networks, and businesses from the 1990s onward. General port-lookup aggregator sites mostly mirror the IANA assignment rather than adding independent sightings, so corroboration beyond FirstClass itself is thin.

Exposure

Restricted — legitimate FirstClass client-server traffic needs to reach the server from outside a single site (remote users, member/community access), but because the protocol is proprietary and undocumented it should be limited to known users and trusted networks (VPN, allowlists, or firewalled access) rather than left open to the whole internet.

CVE/scanning history

No CVE is recorded in the NVD for port 510/udp or the FirstClass protocol as of an August 2026 search, and no dedicated scanning or exposure report (e.g., SANS ISC, Shodan writeup) was found for this port.

Malware/trojan association

Unknown — auditmypc.com's per-port lookup tool, the usual source for a per-port virus/trojan verdict, did not return port-510-specific content in this search, so no verdict can be attributed to it.

Dual registration

Port 510 is registered on both tcp and udp for the same fcp service, so the tcp counterpart carries the same considerations.

IANA assignment

fcp — "FirstClass Protocol"; reference column blank; assignee Mike Marshburn; dual-registered 510/tcp + 510/udp [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry fcp 510/udp

Range class

well-known/system (0–1023) [Confirmed] — the IANA Service Name and Transport Protocol Port Number Registry fcp 510/udp

Prevalence

nmap-services open-frequency 510/udp ≈ 0.000923 (~0.09%); 510/tcp ≈ 0.000063 [Confirmed] — this site's own tooling

Related ports

510/tcp (dual registration of the same fcp service) [Confirmed]

Primary use

FirstClass groupware/messaging protocol used by OpenText's (formerly Centrinity's) FirstClass client-server platform; protocol specification not publicly documented

Other/unofficial uses

none identified in this search beyond FirstClass [Unknown]

Security implications

no CVE recorded in the NVD as of an August 2026 search; malware/trojan status Unknown (auditmypc.com per-port content did not load) [Unknown]

Typically seen on

FirstClass groupware servers/clients — schools, community networks, and businesses

Analyst note

FirstClass is the only application consistently tied to this port; treat unexplained 510/udp traffic as either legacy FirstClass groupware or worth investigating, since no malware association is established either way.