161
snmp
UDP · 0x00A1
Port 161 — snmp
Monitoring
Port 161 carries SNMP polling over UDP. Being at or below 1023, only root may open it on Unix.
0–1023. On Unix only root may open one.
Where it sits in 65535
A port number is 16 bits, so it stops at 65535. The narrow band at the left is everything up to 1023.
065535
- Service
- SNMP polling (snmp)
- Kind
- Monitoring
- Protocol
- UDP
- Range
- Well-known
- Root needed
- Yes
- Hexadecimal
- 0x00A1
- Binary
- 0000000010100001
- Two bytes
- 0 · 161
Same kind
Collecting logs and watching health.
Ports next to it
How to read this
- A port number is 16 bits, so it runs 0 to 65535. There is no port 65536.
- Opening anything at or below 1023 needs root on Unix.
- Plain and encrypted often live on different numbers — 80 and 443, for one.
- Numbers like 3000 and 8080 were never registered; those are marked as custom.
Frequently asked questions
Q. What is port 161 used for?
SNMP polling (snmp) uses it, over UDP.
Q. Does opening port 161 need root?
Yes. It is at or below 1023, so on Unix only root may open it.
Q. Which range does port 161 fall in?
Well-known (0–1023). In hex it is 0x00A1.
Q. Does port 161 have a twin?
Not a separate one. It either was encrypted from the start or negotiates TLS on the same number.