4 ms·

That's from a single machine with 100kPPS. A single cloud machine will get you more, and you can rent a bunch of those. And it's not like you need to scan all

That's from a single machine with 100kPPS. A single cloud machine will get you more, and you can rent a bunch of those. And it's not like you need to scan all of the internet, limiting yourself to the address ranges of the big hosters will cut down the time again. But really, the question is what are you defending against? What's your threat model? There's a published SSH 0-day you didn't patch yet? Ok, maybe that'll buy you a few hours of safety, but that's assuming nobody built a database of reachable ports in advance (think shodan) that they can then rely on to execute these kinds of exploits.

babadaba 6y ago
Do you see how the complexity of the attack increased though? Now the attacker has to buy multiple hosts to stage their attack from. Like anything in life, when things get hard, a percentage of people give up.
- the8472 6y ago
  That's why I mentioned building a database, which essentially evaporates the cost for everyone except the one building the database. Unsalted password hashes are considered insecure due to rainbow tables. And even if nobody built such a database, the cost still seems trivial compared to the effort it would take to compromise SSH in the first place. That is why I asked for a threat model. What are you defending against where everything is cheap except finding the host? If your goal is to cut down on log spam, that's fine, but then just say so.
  - babadaba 6y ago
    > What are you defending against You’re defending against people who wrote scripts that only check the default port. Based on numbers that some others posted, that is actually quite a sizeable number, as they reported numbers of attempted connections on the default port to be orders of magnitude higher than other ports.
    - the8472 6y ago
      Scripts are not magic, they must be doing something. So what are you defending against? The last openssh preauth remote exploit from 2003? Weak passwords? Those are much better addressed by other measures.
      - babadaba 6y ago
        > Scripts are not magic, they must be doing something Not necessarily. Sometimes they just record potential targets for later manual probing. If the script doesn’t find what it’s looking for (in this example the default ssh port), your server is not recorded. That in itself is a win, even if it’s small. > So what are you defending against? It limits the number of people/processes trying to gain access to your server. Would you rather 10 people trying to get in, or 1? > Those are much better addressed by other measures Well, ya. Nobody is saying obscurity is the only security layer. You would need to secure it assuming the port is known. As an additional layer, only to (even slightly) reduce the number of potential threat actors, you change the port.
megous 6y ago
Threat model is having logs flooded by run of the mill automated bot login attempts, and missing the targeted attacks in the noise.
- the8472 6y ago
  If you're monitoring your logs that does make sense. My issue are corporate policies that say "port 22 = bad" but don't monitor the logs either. I don't see what those are defending against. I also disagree with the general statement of the blog post that changing the SSH port is like hiding your tanks. The discrepancy between armor and camouflage vs. cryptography and port numbers is many orders of magnitude. A better explanation than that is needed in my opinion.

babadaba 6y ago

Do you see how the complexity of the attack increased though? Now the attacker has to buy multiple hosts to stage their attack from. Like anything in life, when things get hard, a percentage of people give up.

the8472 6y ago
That's why I mentioned building a database, which essentially evaporates the cost for everyone except the one building the database. Unsalted password hashes are considered insecure due to rainbow tables. And even if nobody built such a database, the cost still seems trivial compared to the effort it would take to compromise SSH in the first place. That is why I asked for a threat model. What are you defending against where everything is cheap except finding the host? If your goal is to cut down on log spam, that's fine, but then just say so.
- babadaba 6y ago
  > What are you defending against You’re defending against people who wrote scripts that only check the default port. Based on numbers that some others posted, that is actually quite a sizeable number, as they reported numbers of attempted connections on the default port to be orders of magnitude higher than other ports.
  - the8472 6y ago
    Scripts are not magic, they must be doing something. So what are you defending against? The last openssh preauth remote exploit from 2003? Weak passwords? Those are much better addressed by other measures.
    - babadaba 6y ago
      > Scripts are not magic, they must be doing something Not necessarily. Sometimes they just record potential targets for later manual probing. If the script doesn’t find what it’s looking for (in this example the default ssh port), your server is not recorded. That in itself is a win, even if it’s small. > So what are you defending against? It limits the number of people/processes trying to gain access to your server. Would you rather 10 people trying to get in, or 1? > Those are much better addressed by other measures Well, ya. Nobody is saying obscurity is the only security layer. You would need to secure it assuming the port is known. As an additional layer, only to (even slightly) reduce the number of potential threat actors, you change the port.

megous 6y ago

Threat model is having logs flooded by run of the mill automated bot login attempts, and missing the targeted attacks in the noise.

the8472 6y ago
If you're monitoring your logs that does make sense. My issue are corporate policies that say "port 22 = bad" but don't monitor the logs either. I don't see what those are defending against. I also disagree with the general statement of the blog post that changing the SSH port is like hiding your tanks. The discrepancy between armor and camouflage vs. cryptography and port numbers is many orders of magnitude. A better explanation than that is needed in my opinion.