Recently, I discovered that SSH of my VPS server is constantly battered as follows.
Apr 06 11:15:14 abastro-personal-arm sshd[102702]: Unable to negotiate with 218.92.0.201 port 53768: no matching key exchange method found. Their offer: diffie>
Apr 06 11:30:29 abastro-personal-arm sshd[102786]: Unable to negotiate with 218.92.0.207 port 18464: no matching key exchange method found. Their offer: diffie>
Apr 06 11:45:36 abastro-personal-arm sshd[102881]: Unable to negotiate with 218.92.0.209 port 59634: no matching key exchange method found. Their offer: diffie>
Apr 06 12:01:02 abastro-personal-arm sshd[103019]: Unable to negotiate with 218.92.0.203 port 16976: no matching key exchange method found. Their offer: diffie>
Apr 06 12:05:49 abastro-personal-arm sshd[103066]: Unable to negotiate with 218.92.0.212 port 49130: no matching key exchange method found. Their offer: diffie>
Apr 06 12:07:09 abastro-personal-arm sshd[103077]: Connection closed by 162.142.125.122 port 56110 [preauth]
Apr 06 12:12:18 abastro-personal-arm sshd[103154]: Connection closed by 45.79.181.223 port 22064 [preauth]
Apr 06 12:12:19 abastro-personal-arm sshd[103156]: Connection closed by 45.79.181.223 port 22078 [preauth]
Apr 06 12:12:20 abastro-personal-arm sshd[103158]: Connection closed by 45.79.181.223 port 22112 [preauth]
Apr 06 12:21:26 abastro-personal-arm sshd[103253]: Connection closed by 118.25.174.89 port 36334 [preauth]
Apr 06 12:23:39 abastro-personal-arm sshd[103282]: Unable to negotiate with 218.92.0.252 port 59622: no matching key exchange method found. Their offer: diffie>
Apr 06 12:26:38 abastro-personal-arm sshd[103312]: Connection closed by 92.118.39.73 port 44400
Apr 06 12:32:22 abastro-personal-arm sshd[103373]: Unable to negotiate with 218.92.0.203 port 57092: no matching key exchange method found. Their offer: diffie>
Apr 06 12:49:48 abastro-personal-arm sshd[103556]: error: maximum authentication attempts exceeded for root from 98.22.89.155 port 53675 ssh2 [preauth]
Apr 06 12:49:48 abastro-personal-arm sshd[103556]: Disconnecting authenticating user root 98.22.89.155 port 53675: Too many authentication failures [preauth]
Apr 06 12:49:51 abastro-personal-arm sshd[103558]: error: maximum authentication attempts exceeded for root from 98.22.89.155 port 53775 ssh2 [preauth]
Apr 06 12:49:51 abastro-personal-arm sshd[103558]: Disconnecting authenticating user root 98.22.89.155 port 53775: Too many authentication failures [preauth]
Apr 06 12:49:53 abastro-personal-arm sshd[103561]: error: maximum authentication attempts exceeded for root from 98.22.89.155 port 53829 ssh2 [preauth]
Apr 06 12:49:53 abastro-personal-arm sshd[103561]: Disconnecting authenticating user root 98.22.89.155 port 53829: Too many authentication failures [preauth]
Apr 06 12:49:54 abastro-personal-arm sshd[103563]: Connection closed by 98.22.89.155 port 53862 [preauth]
Apr 06 12:50:41 abastro-personal-arm sshd[103576]: Invalid user from 75.12.134.50 port 36312
Apr 06 12:54:26 abastro-personal-arm sshd[103621]: Connection closed by 165.140.237.71 port 54236
Apr 06 13:01:26 abastro-personal-arm sshd[103702]: Connection closed by 193.32.162.132 port 33380
Apr 06 13:03:40 abastro-personal-arm sshd[103724]: Unable to negotiate with 218.92.0.204 port 60446: no matching key exchange method found. Their offer: diffie>
Apr 06 13:11:49 abastro-personal-arm sshd[103815]: Received disconnect from 165.140.237.71 port 50952:11: [preauth]
Apr 06 13:11:49 abastro-personal-arm sshd[103815]: Disconnected from authenticating user root 165.140.237.71 port 50952 [preauth]
Apr 06 13:19:08 abastro-personal-arm sshd[103897]: Unable to negotiate with 218.92.0.208 port 59274: no matching key exchange method found. Their offer: diffie>
Apr 06 13:33:36 abastro-personal-arm sshd[104066]: Received disconnect from 165.140.237.71 port 50738:11: [preauth]
Apr 06 13:33:36 abastro-personal-arm sshd[104066]: Disconnected from authenticating user ubuntu 165.140.237.71 port 50738 [preauth]
Apr 06 13:34:50 abastro-personal-arm sshd[104079]: Unable to negotiate with 218.92.0.204 port 44816: no matching key exchange method found. Their offer: diffie>
Apr 06 13:50:32 abastro-personal-arm sshd[104249]: Unable to negotiate with 218.92.0.206 port 27286: no matching key exchange method found. Their offer: diffie>
Apr 06 13:51:58 abastro-personal-arm sshd[104261]: Received disconnect from 165.140.237.71 port 50528:11: [preauth]
Apr 06 13:51:58 abastro-personal-arm sshd[104261]: Disconnected from authenticating user root 165.140.237.71 port 50528 [preauth]
Apr 06 14:01:25 abastro-personal-arm sshd[104351]: Invalid user from 65.49.1.29 port 18519
Apr 06 14:01:28 abastro-personal-arm sshd[104351]: Connection closed by invalid user 65.49.1.29 port 18519 [preauth]
As you can see, it is happening quite frequently, and I am worried one might break in at some point. Since SSH access guards users with root-access, it can be quite serious once penetrated. How do I harden against these kind of attacks? Because this is VPS, disabling SSH is a no-go (SSH is my only entry of access). Are there ways to stop some of these attackers?
As always, thanks in advance!
Using a nonstandard port doesn’t get you much, especially popular nonstandard ports like 2222.
I used that port once and just as much junk traffic and ultimately regretted bothering.
My experience running several ssh servers on uncommon nonstandard ports for over 10 years has been that it has eliminated all ssh brute forcing. I don’t even bother with fail2ban. I probably should though, just in case.
Also, PSA: if you use fail2ban, don’t try tab completing rsync commands without using
controlmaster
or you will lock yourself out.My two cents: Using a nonstandard ssh port is good for dumping bots. True, you can easily do a port scan against a server and easily find all open ports nbd. But most off-the-shelf bots are looking for standard ports to penetrate. I know that when I format and reinstall the test server, as soon as I change the ssh port, bot noise goes down significantly. So, for a simple config edit and about 2 minutes of time, it seems worth the effort. It’s just one layer tho. And yes, it goes without saying to pick a port other than 22, 222, 2222, etc.
How about 22222?
Oh, that one’s fine. Everyone knows that 5-digit ports add extra security, which is why WireGuard runs on port 51820 by default. You can verify this by checking the max port number, which is also 5-digits, computers just aren’t powerful enough to crack 6-digit port numbers, so Linux hasn’t bothered increasing it. /s
It gets rid of most of the login attempts for me. I don’t use a popular port though. Pick a 5 digit port so they have to put in some effort to find it.