JACKPROBE

Portable network drop tester

Plug it into the jack.
It tells you if the drop is good.

Link, addressing, reachability and the switch port behind the wall, in about half a second, from a device that fits in a pocket and needs no laptop, no account and no cloud service.

PASS This drop is good. Link, addressing and internet reachability are all healthy.

What it measures

One question, answered from the wall plate

Physical

Link

Up or down, speed and duplex. Ten and a hundred megabit; this is not a gigabit tester.

Layer 3

Addressing

Whether DHCP offered an address, and what it offered: IP, mask, gateway and DNS server.

Reachability

Gateway, DNS, internet

Judged by traffic actually flowing through the gateway rather than by ping, because plenty of gateways drop ICMP and a tester that calls that a failure sends people chasing faults that are not there. Reachability is proven by completing a TLS handshake, which a captive portal cannot answer, against a target you can change.

Latency

Round trip, in milliseconds

ICMP to the gateway, reported separately from the reachability verdict, so a slow gateway and an unreachable one are different answers.

Identity

Public address

How the drop is seen from the internet, which is often the fastest way to tell which of two uplinks you are actually on.

Verdict

PASS, WARN or FAIL

One answer, on the LED and at the top of every report, so the person holding it does not have to interpret six readings.

Overheard

Did this port ask for credentials?

It listens for the switch's 802.1X identity request and tells you when one arrives, and whether an address was handed out anyway. It can never tell you a port does not use it, and it does not pretend to.

Overheard

What else answers DHCP here

A second DHCP server is a real outage, and it is usually a small router somebody put in a wall port. Both are named, with the MAC address of each, which is what finds the port it is on.

The part that saves the walk

Which switch, which port, which VLAN

Switches announce themselves. LLDP and CDP advertisements name the device, the port an advertisement came out of, and often the VLAN. The tester listens for them and reads what arrives.

It transmits nothing to obtain this. There is no scan, no probe and no query to the switch, so nothing appears in a log and nothing needs a credential. You stand at the wall plate and the jack identifies the port it lands on.

It depends on the switch. These fields are read from advertisements the switch already sends onto the wire. Where a switch has LLDP and CDP disabled, or does not advertise toward access ports, the fields stay empty and the tester says so rather than guessing.

Switch, read passively

DeviceUSW-Flex
Porteth0
Management IP10.1.0.35
VLANnot advertised

An actual reading, from the switch this unit was tested against. The VLAN row is what an empty field looks like.

How you read it

Three ways, all showing the same result

A light

Green, amber or red the moment the test finishes. Enough to walk a floor of jacks with nothing in your hand but the tester.

A web console

The tester runs its own WiFi hotspot. Join it from a phone and open the console: live readings, the saved reports, and the settings. No app to install and no internet needed.

A report you hand over

One self-contained HTML file per saved test, carrying the label and notes you type, the switch and port it saw, and both local time and UTC. It opens in any browser, forever, with nothing else installed.

Read the manual for every control, gesture and menu.

Before you buy

What it does not do

A specification that admits its limits is the one worth trusting. None of the following is planned, hidden behind a licence, or coming in a later firmware.

Not thisWhat that means for you
Power over Ethernet No PoE detection and no PoE measurement. It will not tell you whether the port supplies power, at what class, or on which pairs.
Cable certification No wiremap, no TDR, no cable length, no distance to fault. It cannot be used for structured cabling warranties. It tests whether the drop carries a working network, which is a different question from whether the cable meets a standard.
Gigabit Ten and a hundred megabit only.
802.1X authentication It is not a supplicant and carries no credentials, so it will not get onto a port that demands them. It does listen, and it will tell you when a port asked. It can never tell you a port did not.
IPv6 Not tested.
Capture and survey No packet capture or inspection for you to read, no spectrum analysis, no survey of surrounding WiFi networks.

The questions page goes further into each of these, including what you actually see on a port that needs 802.1X.