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I have two Windows 10 PCs and one Fedora 33 Linux machine (all physical machines) on my home wireless network, using ASUS RT-AC3200 router powered by Asuswrt Merlin version 384.13_10.

I am attempting to ssh and rdp from Windows PC 1 to Fedora machine. Neither work. PC2 can ssh and rdp to the Linux machine with no problems (rdp using xrdp with tigerVNC server on Linux)

It appears that something is preventing PC1 and Linux machine from seeing each other, but I can't put my finger on it.

Pinging the Linux machine From PC1, I get

    Pinging 192.168.1.234 with 32 bytes of data:
    Request timed out.
    Request timed out.
    Request timed out.
    Request timed out.
    Ping statistics for 192.168.1.234:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Which indicates that the signal went out from PC1, but it received no reply from the Linux box.

Pinging PC1 from the Linux box, I get

     [lith@localhost ~]$ ping 192.168.1.126 -c 4
     PING 192.168.1.126 (192.168.1.126) 56(84) bytes of data.
     From 192.168.1.234 icmp_seq=1 Destination Host Unreachable
     From 192.168.1.234 icmp_seq=2 Destination Host Unreachable
     From 192.168.1.234 icmp_seq=3 Destination Host Unreachable
     From 192.168.1.234 icmp_seq=4 Destination Host Unreachable

     --- 192.168.1.126 ping statistics ---
     4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 3109ms
     pipe 3

Which indicates that there is no route from Linux to PC1.

As indicated earlier, PC2 and Linux machines can ping each other, and I can establish both SSH and RDP connections from PC2 to Linux machine. furthermore, Linux machine can successfully ping most everything on the network, including devices such as a smart TVs, sound systems, garage door openers, etc- it just can't ping PC1.

EDIT1: Requested information from the comments

PC1: (cannot connect to linux box)

IP: 192.168.1.126 Netmask: 255.255.255.0 Gateway: 192.168.1.1

PC2: (can connect to linux box)

IP: 192.168.1.201 Netmask: 255.255.255.0 Gateway: 192.168.1.1

Linux:

IP: 192.168.1.234 Netmask: 255.255.255.0 Gateway: 192.168.1.1

EDIT 2: PC1 is able to ping other devices on the network, including PC2. IP addresses are assigned by DHCP, via the router. The other interesting thing is that when run arp -a on the linux box, I can see PC1's IP and mac address.

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  • Are you totally sure the network addresses and netmask are as you've written them here? (A copy-paste avoids you writing what you think you saw, rather then what it is.)
    – roaima
    Dec 30, 2020 at 0:47
  • Are there other devices on the LAN? If so please disconnect (or switch off) PC1 and then try to ping it from the Linux box
    – roaima
    Dec 30, 2020 at 0:47
  • I double and triple checked. Yes, this is the correct information. I turned off PC1 and pinged from linux box, and had the same thing- Destination Host Unreachable. However, I then turned off the linux box and pinged it form PC1. This time, I get Destination Host Unreachable, which is different than what it reports when turned on (Request timed out). It appears that when the linux box is on, the ping is sent from PC1, the linux box just doesn't bother replying.
    – Lithophile
    Dec 30, 2020 at 14:49
  • Great. Can you check your Linux firewall please (if it's iptables then run these as root, iptables -nvL; iptables -t nat -nvL). Ideally paste the whole lot into your question, but the aim is to see whether there are rules discarding relevant traffic. There shouldn't be, but I'm running out of ideas
    – roaima
    Dec 30, 2020 at 15:28
  • iptables is legacy in Fedora 33, and not in use. I went ahead and disabled and masked it to be sure. I'm currently using Firewalld, which I have disabled completely at this point (stopped, disabled, and masked). What information are you wanting from iptables? I'm not familiar with iptables, but I can see to getting it out of firewalld.
    – Lithophile
    Dec 30, 2020 at 19:37

1 Answer 1

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OK so you haven't said what PC1 can ping. But from the sounds of things this is where the problems lay.

If you are manually assigning IP's, it's possibly a typo. Treble check what you think you know.

The approach I would use:

  • Can PC1 ping anything.
  • Can the router see PC1 (there's tools in the router to ping things).
  • Can PC2 see PC1.

If none of the above can be done, defo the PC causing the problems.

If some or all of the above is possible, more likely a firewall issue. Double check if there is a firewall running on PC2, turn it off, still a problem?

Changing the IP address of PC2 might be a good idea too, just in case.

Having the PC get it's IP via DHCP (assuming it doesn't already) confirms that the is some communication going on.

If none of this helps. Come back with a bit more info based on my suggestions please.

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  • That's fair- I did omit PC1's accessibility. PC1 can ping pretty much anything except for the linux box, including smart devices, mobile phones, etc, and PC2. PC2 can ping PC1 and other devices as well. I will have to get back to you on whether the router can ping PC1, as I've never tried that, but I can confirm that both linux box and PC1 can ping the router. I can see activity on both PC1 and linux box in the router's traffic analyzer when accessing internet on each device as well.
    – Lithophile
    Dec 30, 2020 at 0:05
  • I can also confirm, I am not manually assigning IPs- all through DHCP.
    – Lithophile
    Dec 30, 2020 at 0:11
  • At that point I would assume the next most likely is a firewall issue, on one or the other. Do you have the firewall turned off on both. I must confess the "distance" apart for the IP's 126 to 234 is pretty big on a home network, I am assuming you have a massive DHCP lease time, otherwise that seems a little odd to me. I've a pretty busy home network, and mine are all pretty much at the start of the pool, certainly nothing over 100 apart. Also can you RDP from PC1 to PC2 and vice versa?
    – Netspud2K
    Dec 30, 2020 at 11:01
  • And if you can ping from other stuff, pinging from the router is not going to tell us much I doubt.
    – Netspud2K
    Dec 30, 2020 at 11:01
  • I would think that too, but I can confirm that both computers' firewalls are disabled. windows defender is disabled for both public and private network settings, and systemctl status firewalld reports inactive (dead). I'm not able to RDP from PC1 to PC2, but that's due to security on PC2 (it's a work laptop). I can however RDP from PC2 to PC1.
    – Lithophile
    Dec 30, 2020 at 14:45

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