Common Network Ports Cheat Sheet for Network+, Security+ and CCNA
By Samuel Cuadrado, founder of BoardITGuy (BoardXGuy LLC). Updated 2026-10-27.
Ports and protocols show up on Network+, Security+, A+, CCNA and most other IT exams, and they are the thing students most often say they cannot keep in their heads. This sheet is grouped by what the service does, with the secure version next to the plain one, because the pairs are what exams ask.
Use it as a reference, then recall it with flashcards instead of rereading it. Learning the groups first is much easier than learning the numbers one at a time.
Remote access and file transfer
| Service | Port | Transport | Notes |
|---|
| SSH (and SFTP, SCP) | 22 | TCP | Encrypted remote shell. SFTP and SCP run inside SSH. |
| Telnet | 23 | TCP | Plain text. Replaced by SSH. |
| FTP | 20 and 21 | TCP | 21 is control, 20 is data in active mode. Plain text. |
| FTPS | 990 (implicit), or 21 with STARTTLS | TCP | FTP wrapped in TLS. Not the same as SFTP. |
| TFTP | 69 | UDP | Simple, no authentication. Used to boot devices and move configs. |
| RDP | 3389 | TCP (and UDP) | Windows remote desktop. |
| VNC | 5900 and up | TCP | Remote screen sharing. |
Web
| Service | Port | Transport | Notes |
|---|
| HTTP | 80 | TCP | Plain text. |
| HTTPS | 443 | TCP | HTTP over TLS. |
| HTTP alternate | 8080 | TCP | Common for proxies and test servers. |
Email
| Service | Port | Transport | Notes |
|---|
| SMTP | 25 | TCP | Server to server mail transfer. |
| SMTP submission | 587 | TCP | Clients sending mail, normally with STARTTLS. |
| SMTP over TLS (implicit) | 465 | TCP | Older implicit-TLS port, still used. |
| POP3 | 110 | TCP | Downloads mail. POP3S (secure) is 995. |
| IMAP | 143 | TCP | Keeps mail on the server. IMAPS (secure) is 993. |
Names, addresses and time
| Service | Port | Transport | Notes |
|---|
| DNS | 53 | UDP and TCP | UDP for normal queries, TCP for large answers and zone transfers. |
| DNS over TLS | 853 | TCP | Encrypted DNS. |
| DHCP | 67 (server), 68 (client) | UDP | Hands out addresses. |
| NTP | 123 | UDP | Time synchronisation. |
Directory, authentication and logging
| Service | Port | Transport | Notes |
|---|
| Kerberos | 88 | TCP and UDP | Ticket-based authentication. |
| LDAP | 389 | TCP and UDP | Directory queries. LDAPS (secure) is 636. |
| RADIUS | 1812 (auth), 1813 (accounting) | UDP | Older deployments use 1645 and 1646. |
| TACACS+ | 49 | TCP | Cisco device administration. |
| Syslog | 514 | UDP | Log forwarding. Syslog over TLS is 6514. |
| SNMP | 161 (queries), 162 (traps) | UDP | Device monitoring. SNMPv3 adds authentication and encryption. |
File sharing and databases
| Service | Port | Transport | Notes |
|---|
| SMB | 445 | TCP | Windows file sharing. Older NetBIOS uses 137, 138 and 139. |
| SQL Server | 1433 | TCP | Microsoft SQL Server. |
| MySQL | 3306 | TCP | MySQL and MariaDB. |
| PostgreSQL | 5432 | TCP | PostgreSQL. |
VPN, voice and routing
| Service | Port or number | Transport | Notes |
|---|
| IKE (IPsec key exchange) | 500 | UDP | Sets up IPsec. NAT traversal uses 4500. |
| SIP | 5060 (5061 with TLS) | UDP and TCP | Voice and video call signalling. |
| BGP | 179 | TCP | Routing between networks. |
IP protocol numbers (not ports)
Some protocols ride directly on IP and have a protocol number instead of a port:
| Protocol | Number |
|---|
| ICMP | 1 |
| TCP | 6 |
| UDP | 17 |
| GRE | 47 |
| ESP (IPsec) | 50 |
| AH (IPsec) | 51 |
| EIGRP | 88 |
| OSPF | 89 |
How to remember them
- Learn pairs. For each plain service, learn its secure twin: HTTP and HTTPS, LDAP and LDAPS, IMAP and IMAPS, POP3 and POP3S, Telnet and SSH.
- Group by purpose. Email, names, remote access and directory services each form a small set.
- Know the transport. DNS, DHCP, TFTP, NTP, SNMP and syslog are UDP by default. Most of the rest is TCP.
- Recall, don't reread. Run the ports as flashcards a few minutes a day; each one comes back just before you'd forget it.
- Test it the way exams ask. Practice questions describe a symptom (users can't resolve names, mail won't send) and make you pick the port, so answer some once the numbers feel solid.
Exams sometimes use a slightly different port for a service than the one real networks do, so when a practice question and a vendor document disagree, trust the vendor's current exam objectives.
The CompTIA Network+ study board and the CompTIA Security+ study board put these on a visual map next to the topics they belong to, and the flashcards drill them.
See the study boards More guides