Why is pfSense calling CZ?

November

This morning I noticed the following DENY logged: Jul 22 05:00:05 LAN pfB_Europe_v4 (1770012069) TCP-S 192.168.1.100:40068 87.236.194.23:443 unassigned-87.236.194.23.cool... CZ Country.

What can I do to trace back the origin of this call (I'm assuming, perhaps incorrectly, that the 192.168.1.100 IP means that pfSense is forwarding a call from somewhere else)?

DaddyGo

@November said in Why is pfSense calling CZ?:

noticed the following DENY logged:

this means that you have set pfBlockerNG to full European IPv4 blocking
(it doesn't make much sense to block such a huge IPv4 range!!!)

192.168.1.100 is the IP address of the pfSense box? (or an internal host address?)

pfBlockerNG intercepted TCP-"syn" and blocked it as it started towards CZ IP address

otherwise, this IP belongs to a Czech "hosting provider"

nslookup (sorry to show you in writing but can't post pictures in the forum, today):
unassigned-87.236.194.23.coolhousing.net (maybe it could be some CDN stuff)

https://www.coolhousing.net/en

+++edit:
if you definitely think you want to protect yourself by blocking complete IP ranges (not a good idea), choose between the ones that are threatening via (e.g., DDoS, CoinMiner, botnet, etc.)
these can help:

https://www.cybersecurity-insiders.com/list-of-countries-which-are-most-vulnerable-to-cyber-attacks/
https://www.digitalattackmap.com/#anim=1&color=0&country=ALL&list=0&time=18464&view=map
https://talosintelligence.com/

November

@DaddyGo ,

Yes, I've chosen to block CZ. I understand that in theory this shouldn't do anything. Considering something is trying to call CZ when no one in the household is awake, I'd like to know what that is.

The firewall's IP address is 192.168.1.1. I'm assuming 192.168.1.100 is coming from the firewall, too, since the LAN IP addresses don't start with 192.168.1. Perhaps this is a flawed assumption. If it is, it sounds like I should start blocking all calls from 192.168.1.100 until I can track down its source.

provels

@November said in Why is pfSense calling CZ?:

87.236.194.23

Could be this CZ IP was sold/leased to someone else, maybe an ad server or such. Perhaps innocuous or perhaps you have malware. What device is 192.168.1.100?

DaddyGo

@November said in Why is pfSense calling CZ?:

it sounds like I should start blocking all calls from 192.168.1.100

this would be a very rough intervention
detection, debugging (if any at all), it doesn't have to be this way

what kind of device's IP address is 192.168.1.100

if we find out what triggers requests from the device to CZ
you can take action..

+++edit:
probably some application initiates requests to this hosting provider on an intermediate network (CDN, datacenter IP, etc.)
this is not a real location, but it uses an https port

BTW: the request does not reach because pfBlockerNG is working

do you hate CZ?

November

@provels "What device is 192.168.1.100?" is one of the root questions I'm trying to answer. Currently I'm turning off one or two devices at a time to try to track down which device it is. Any other suggestions?

November

@DaddyGo , I don't hate CZ but from what I've read and from my own experience working at a global Internet company, lots of hacking starts from that area.

jdeloach

This post is deleted!

ptt

@jdeloach said in Why is pfSense calling CZ?:

IP address ~~192.168.1.100~~ is the common address of most cable modems. This has always been the IP address of all cable modems that I've had in the past.

192.168.100.1 ;)

provels

@November
Ping 192.168.1.100 then do and

arp -a

to see what MAC address has 1.100 and track down the MAC.

PS C:\Users\Me> arp -a

Interface: 192.168.0.20 --- 0x17
  Internet Address      Physical Address      Type
  192.168.0.1           00-15-5d-00-14-30     dynamic
  192.168.0.12          00-15-5d-00-14-2c     dynamic
  192.168.0.61          00-11-0a-54-23-14     dynamic
  192.168.0.69          00-15-5d-00-14-4b     dynamic
  192.168.0.71          fc-03-9f-f8-86-d8     dynamic
  192.168.0.100         0c-41-3e-91-6e-60     dynamic
  192.168.0.101         30-0d-43-26-00-e8     dynamic
  192.168.0.106         00-15-5d-00-14-45     dynamic
  192.168.0.108         00-1e-64-4d-d0-2e     dynamic
  192.168.0.111         00-15-5d-00-14-2d     dynamic
  192.168.0.150         30-52-cb-e7-50-71     dynamic
  192.168.0.200         00-00-f0-a3-f3-33     dynamic
  192.168.0.204         00-09-b0-e6-5c-b0     dynamic
  192.168.0.255         ff-ff-ff-ff-ff-ff     static
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  224.0.0.252           01-00-5e-00-00-fc     static
  239.255.255.250       01-00-5e-7f-ff-fa     static

Or try a


ping -an

and maybe it will resolve the device name.

PS C:\Users\Me> ping -an 192.168.0.150

Pinging XPS13 [192.168.0.150] with 32 bytes of data:
Reply from 192.168.0.150: bytes=32 time=5ms TTL=128
Reply from 192.168.0.150: bytes=32 time=7ms TTL=128
Reply from 192.168.0.150: bytes=32 time=5ms TTL=128
Reply from 192.168.0.150: bytes=32 time=9ms TTL=128

November

@ptt , it turns out that 192.168.1.100 is the WAN IP address that my router is using.

Thanks much, everyone!

The question now is why my router is calling out to CZ, UA, etc.

provels

@November
Well, there are router exploits. You may want to search for your model and exploits.

November

@provels , that's definitely one of my concerns.

I was just made aware of https://atlas.ripe.net/landing/probes-and-anchors/. Whenever I've done a who.is on the target IP addresses, RIPE does come up. I'll try whitelisting them and seeing if that helps.

provels

@November
Maybe check here:
https://duckduckgo.com/?isource=infinity&iname=duckduckgo&itype=web&q=router+exploits+by+manufacturer&atb=v211-1&ia=web

DaddyGo

@November said in Why is pfSense calling CZ?:

lots of hacking starts from that area.

Interesting..

CZ country next to my place of birth, but I haven't heard of them yet such as harassment, hackers, etc., I worked as a computer scientist in Brno (city CZ) for a long time and it never arose.

I accept your position, if you feel that way