Cross Post - Help sorting out a Firewall Issue on a Debian Box



  • Op HERE

    "I have a debian box (i know nothing about linux for most part but I do know networks) and when I am on the same subnet as the device I can ping it just fine however if I move to another vlan we have here I cannot ping the device. Other devices on the two networks ping just fine its only this one device that wont ping from the other network. No sonicwall rules or anything are blocking everything is open both ways. The issue has to be with this linux device not responding for some reason but I have know idea what to look for. "



  • A default gateway on the debian box?



  • "Probably the IPTables firewall on the Debian box blocking the ICMP requests from subnet other than it's LAN.

    Or less likely a routing issue

    Do

    iptables -L
    to see the rules for the firewall
    and

    route
    to see the routing table"

    Response:
    "i did that following the steps here https://wiki.debian.org/iptables and it just made things worse to where I couldnt even ping it locally anymore so I am trying to back track and doing it in the dark because my boss thinks I should be able to learn linux in 3 hours and fix this issue for him. I THINK i set the iptables back to default where they were but I am not sure nor do i know if the default IPtables are what I want. I cant copy and past the information here cause I cant SSH into the damn thing right now.

    I dont even know how to verify if the ipaddresses are still setup on this thing. I did a ifconfig -a and I see the wlan and 2 eth ports but no ip adddresses at all except the loopback address.... im totally lost now. "



  • Do you have access to the debian box currently? If so how are you accessing the system?



  • To see if you have internet connectivity on this system, you could simple do a ping 8.8.8.8.

    If it resolves then you have an IP address.



  • ifconfig -a should list all of the network interfaces and what they're configured for.

    Alternatively you can use ip addr which is the standard.



  • @Dashrender said in Cross Post - Help sorting out a Firewall Issue on a Debian Box:

    A default gateway on the debian box?

    My thought. I don't think I've seen a system firewall not accept icmp by default.

    If you stop iptables and still can't ping it's not the firewall.



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