Unknown ssh connections

Posted on July 7, 2020

I just checked the ssh connections logs, because my public bandwidth is unusually high and found this:

tcp   ESTAB       0       1080                         68.183.77.132:ssh                                       61.177.172.158:49833
tcp   FIN-WAIT-1  0       1                            68.183.77.132:ssh                                      222.186.180.223:22882
tcp   ESTAB       0       36                           68.183.77.132:ssh                                       *MYIP*:61630
tcp   ESTAB       0       1080                         68.183.77.132:ssh                                       61.177.172.158:21058
tcp   ESTAB       0       1080                         68.183.77.132:ssh                                         218.92.0.248:47166

All of these except mine are chinese ips. I looked them up and they are all from the “Asia Pacific Network Information Centre”. Not sure what to do now with this information, but I don’t like it. Do I need to worry?

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alexdo

July 8, 2020

Hi, @EMokro

You can block every IP address that makes unsuccessful ssh authentication as this is clearly not a legit traffic. You can install CSF (Config Server Firewall) and they will be automatically blocked and you can also set rules to block whole regions and countries.

You can also look into changing the ssh port and make only the pubkey authentication is enabled leaving the password authentication disabled in order to keep things safe. Also make sure everything on the droplet is updated and you’ve blocked/closed all the ports which are not used.

Brute force login attacks are one of the most common ways for a server to be compromised. This tutorial shows you how:

[How To Configure SSH Key-Based Authentication on a Linux Server](https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-linux-server)

Hope that helps!

Regards, Alex