Network ports — memo form

Remote Unix/Linux administration; prefer keys and network filtering.

UDP common, TCP for large responses/transfers and other cases.

Broadcast/relay depending on architecture.

Critical for Kerberos

Prefer SNMPv3 where possible.

Active Directory also requires RPC/Kerberos/DNS.

LDAP over TLS; check certificate and trust chain.

Used by Active Directory global catalog.

Often redirected to HTTPS but may still be required for some services.

Major application port; inspect TLS/SNI/Host beyond TCP.

Remote PowerShell management on Windows.

WinRM over TLS; requires correct certificate/configuration.

Server-to-server mail transport.

Depending on provider/service.

Common authenticated client/application submission port.

Mailbox access, separate from SMTP sending.

AD authentication; also depends strongly on DNS and NTP.

RPC then uses dynamic ports depending on OS/configuration.

Highly sensitive to Internet exposure.

Modern default dynamic RPC range, configurable.

Default classic SQL Server port; named instances may differ.

Do not expose publicly without strong justification and controls.

Filter DB access by source and authentication.

Unprotected exposure is especially risky.

IKE negotiation.

Used when NAT is detected.

Does not cover RTP media, whose range depends on the platform.

Exact requirements depend on components and flow direction.

Tests TCP from the client point of view.

Tests TCP if netcat is installed.

Confirms a local service is listening.

Maps ports and processes when permissions allow.