Comment on Thoughts on crowdsec
The_Zen_Cow_Says_Mu@infosec.pub 1 day ago
i run it on opnsense. When my services were on individual subdomains each with their own certificate, they got hit a lot and crowdsec blocked lots of bots and scripts
I ultimately moved all my services to a wildcard sub-subdomain, and poof all the bots went away and now crowdsec doesn’t do much other than block port scanners which the firewall does anyway.
it’s not worth the hassle to uninstall though.
I also haven’t seen any bot activity after I started using wildcard sub domains. My ISP blocks all incoming on common ports so I also use uncommon ports. I assume the combination of the two makes it too time consuming to find me.
I hid my ssh port with a wireguard connection so I also don’t see any attempts on my ssh port anymore either. My logs, including fail2ban, are quiet and boring.
It’s nice to have a quiet corner of the internet for myself.
irmadlad@lemmy.world 16 hours ago My logs, including fail2ban, are quiet and boring.
Every once in a while, I’ll tail my f2b logs, almost half heartily hoping I find an anomaly. But, no…it’s a snoozefest. pFsense out there on the edge, just doing it’s job.
Ahh so bots are finding subdomains by scraping SSL certificates?
That was my experience also. Within minutes of spinning up any new subdomain with a dedicated A DNS record, I had bots that scraped it from crt.sh knocking on the door.
With wildcard subdomains and relatively obscure URLs, it’s pretty quiet.
lemmyvore@feddit.nl 20 hours ago
Yes, and also by trying common subdomains under the main domain (like
jellyfin.,home.etc.) (They also scan the entire IPv4 address space, all TCP ports, over and over, but that’s a different discussion.)If you’re using DDNS you have to also be careful where you put the
AandAAAArecords. Some people put them on the main domain and then do a wildcardCNAMEpointing to it for all the subdomains, or individual subdomainCNAMEs. But since the main domain is known from TLS cert logs it’s trivial for bots to also check to see if there’sA/AAAArecords on it.It’s better to put the
A/AAAAon a dedicated subdomain, obfuscate the name beyond trivial guesses (eg. maybe don’t useip.), and make an individualCNAMEfor each services that points to the IP subdomain, and obfuscate those service subdomains similarly.For those who aren’t familiar with DNS, the information in it is publicly available to anybody who can name a [sub]domain and record type explicitly, but they refuse to do “list all the records for all the subdomains of this domain”. So bots are limited to asking for the most commonly used record types on the main domain but can’t guess subdomain names. (For completion, asking for a list of all records is possible, but nowadays due to abuse that function is restricted on all the public servers to just the known IPs of their fellow redundant servers.)
Even after taking these measures you have to keep in mind that this is not security, it’s obscurity. It cuts down on bot scans which is great but don’t assume it means nobody knows your service domains. Your ISP probably knows them, there are DNS servers out there that know them, your mobile carrier can see them, and if you ever connect to WiFi when away from home the owners of those WiFi can see them (think hotels, airports, coffee shops etc.) It’s not out of the question for a coffee shop WiFi to have been compromised and to collect URLs and attempt attacks against them. Use VPN or a SSH tunnel to connect to services whenever possible, rather than exposing them publicly.