Linux systems unable to reach out to internet behind pfsense while Windows work fine.

I am trying to set up my #homelab for #forensics and I have encountered a very weird issue. I am running an internal pfsense #firewall for my environment. On this firewall there are 3 interfaces: WAN and two Isolated Labs.

On the “WAN” interface, both #linux and windows systems are able to access the internet without any problems.

But on the other two lans - named Infrastructure and Lab - the Linux systems are not able to connect to the internet after booting, while the systems are able to communicate with each other. In order to get them working I need to go the respective interface and make any change there and save the page, practically refreshing the settings on the interface. After this all currently online linux systems on that interface are working as expected and connectivity is restored. As you can imagine this is a huge pain, especially when I am testing things and I need to turn on various systems at different times. If i put the systems on the WAN interface they face no issue at all, so what could be the solution here for fixing connectivity for linux systems on the other interfaces?

edit: it issue is both on pfsense 2.7.2 and 2.8.0

@homelab
@pfSense

#dfir #proxmox #dfir #homelab #firewall #pfsense #networking #network

  • 0xCDE@infosec.exchangeOP
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    11 days ago

    @Chewt
    yes they can still ping my firewall while not connected to the internet.
    Here are two screenshots from one of the ubuntu vms on the home network and one from the kali vm on the infra network

    ip -br a output ip route output ip route and ip -br a output

    • Chewt@beehaw.org
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      11 days ago

      Well that doesn’t really indicate any problems with the default gateway. My last bit of troubleshooting advice is to traceroute and see if packets get stuck at the router. And check the firewall logs in pfsense to see if you can find anything there.

      Hopefully it ends up being a relatively painless problem to fix!

      • 0xCDE@infosec.exchangeOP
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        3 days ago

        @Chewt found the issue in the end… i had two interfaces share the same IP and was creating a conflict on the linux hosts. I dont know why Windows was not affected by it but all good in the end

        • Chewt@beehaw.org
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          3 days ago

          Happy to hear it! Address conflicts are always a pain, I recently ran into an issue with my VPN to my home network, where my home network and the network I was on shared the same subnet and mask, so I had to specify some custom routes to make it work. Good network design is a must to try and mitigate these things!