Question

Is anyone else being brute forced by Chinese IP addresses?

Posted April 21, 2015 11k views
SecurityMonitoringLogging

So for the past few days i'v been keeping track of my fail2ban logs and noticed that a ton of Chinese ip addresses are being banned. It seems from my auth.log they are trying to brute force there way into my root account. I was wondering if anyone else is experiencing this and if its something I should report directly to DigitalOcean?

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8 answers

Welcome to the club, it’s nothing unusual.

This is not at all unusual for any server on the public Internet. There are a few steps you can take to reduce the risk from this. You have indicated you already set up fail2ban which is a great step.

You can change your ssh port. Since most of these brute force attacks are automated and usually target the default port 22 this would further reduce the number of attacks on your ssh service.

You could set up CloudFlare’s free reverse-proxy plan in front of your droplet. Since ssh is not proxied a user looking up your domain name would only receive a CloudFlare IP. This will not prevent indiscriminate scans but would help a lot with any attack that may be targeted at your domain.

You can report these instances to the network operator of the IPs you are detecting. Operators in many countries will take action against this activity, unfortunately in others these reports may be ignored. You can usually find the abuse email address by performing a whois on the ip address:

example:

whois 8.8.8.8

Thanks for the tips. I will for sure be switching to cloudflare I didn’t realize they had a free plan and I will also switch the default port of my ssh. Is it good practice to also switch the default port of my web server?

In the past week it looks like a big block 43.255.190.* has been brute forcing constantly. Once an IP gets banned it simply goes to the next in the block and continues.

  • Yup those are the ip’s that i’m seeing. After changing the default ssh port they seem to have stopped completely. So they must be just targeting servers with the default port of 22.

I use this to help track and help block these assbaskets: https://www.abuseipdb.com/

Still happening. I had to switch our services to a whitelist instead of bothering to block the literally billions of addresses (address ranges) attacking us. It looks like all of the ISPs in China are using large swaths of their compute capability to attack outside systems.

Yes, back in 2019, I started working on improving the security of the SSH login to our database, and I noticed Linux’ logs showing a lot of login attempts. As I continued blocking new addresses, I started tracing them, and found that 99.9% were from Chinese ISPs. I figured it must be state sponsored, since these attacks were coming from all over the country (with just a few exceptions, e.g., a couple of Amazon AWS accounts). My solution was to change to an allow-only list, since I had blocked literally billions of addresses, and it wasn’t enough. For the past couple of years, this has remained an effective mitigation.