this port’s kinda crazy, hack me maybe

29 Jul, 2025

“It’s just for monitoring.” Cool. So’s CCTV — doesn’t mean I want it livestreamed to the public internet.

🤷‍♂️ So What the Hell Is SNMP? SNMP stands for Simple Network Management Protocol, which is a fancy way of saying:

“Oi mate, tell me everything about your router... and maybe your switch, your firewall, your fridge, your dog’s GPS collar — whatever’s listening on UDP/161.”

It’s old as dirt, speaks over UDP (because who needs reliable packets?), and comes in three flavours of regret:

v1 – "No security, just vibes"

v2c – "Still no security, but now with community strings!"

v3 – "Finally secured, which is why nobody uses it"

🪓 Why It’s Absolutely Still a Problem in 2025 🔑 Default Strings Like public and private Mate. If I had a dollar for every time I popped a device with snmpwalk -c public, I’d be buying CISOs a round at the pub. These strings are supposed to be changed. You didn’t. I found it. Cheers.

🧠 No Authentication (v1/v2c) SNMPv1/v2c is basically yelling secrets into a megaphone on Swanston Street. No login. No encryption. No shame.

📬 UDP = Fire and Forget It’s like sliding a note under the door and praying for a reply. But SNMP? It’s the chatty bloke inside who always responds with full config dumps and your interface MACs.

📤 Information Buffet Here’s what I can learn just by whispering "g'day" to port 161:

Hostname

Uptime

Interfaces

Routing tables

Active processes

Possibly your admin usernames

Maybe even config backups (don’t laugh, I’ve seen it)

🔍 What I Do When I Sniff It Step 1: Nmap and a Bit of Hope bash Copy Edit nmap -sU -p 161 -Pn --script snmp-info,snmp-interfaces Oh? Port open or open|filtered? Looks like Christmas came early, cobber.

Step 2: SNMPwalk the Plank bash Copy Edit snmpwalk -v2c -c public 1 Still works in 2025. Still makes people cry. If that works, I will try private, cisco, monitor, and the name of your company in lowercase.

Step 3: Brute It Because Of Course bash Copy Edit onesixtyone -c wordlist.txt Don’t worry — your “security through obscurity” string like snmp12345 isn’t fooling anyone. I’ve got a wordlist, a longneck, and no weekend plans.

🐨 A Totally Real Story During a gig, I found SNMP on a public-facing NetScaler (because of course it was). Using snmpwalk, I got:

The internal naming convention

IP ranges and interface details

The routing table, which was a bloody mess, by the way

Bonus: exposed a legacy Solaris box that hadn't been patched since Kevin07

All from one UDP packet and a questionable life choice made in 2009.

🛡️ How to Not End Up in My Blog Post If you're using SNMP, and you enjoy not being featured in a “Shodan Hall of Shame,” do this:

Use SNMPv3 – yeah, it's annoying, but so is a breach report

Block SNMP at the perimeter – because the internet isn’t your mate

Lock SNMP to your monitoring server via ACLs – not "0.0.0.0/0" you absolute maniac

Change default community strings – I know yours is still public

Log it – so you know when I try

Turn it off – seriously, when’s the last time you used SNMP on a printer for anything useful?

🧼 Final Rinse SNMP is like that bloke who’s always half-dressed at the servo:

Old

Loud

Absolutely oversharing

And like him, you really don’t want him exposed to the internet.

If you’re running SNMP on prod gear, exposed to the public, with public as the string — congratulations. You’ve built a honeypot. Unfortunately, it’s your real environment.

Stay patched, stay paranoid, and for god’s sake, stop leaving UDP ports open. I’ve got snmpwalk on hotkey and no self-control.