Hello,
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
What am I doing wrong?
Thank
=========================================================================== Patrick DUPRÉ | | email: pdupre@gmx.com ===========================================================================
On 3/1/25 7:03 AM, Patrick Dupre via users wrote:
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
What am I doing wrong?
Your description is very unclear. PC B is connected through a telephone??
Assuming it's actually a normal ethernet connection to the internet, PC B will need two ethernet cards. I don't understand how you have it connected right now.
I am lost.
I had a configuration with was working, but my usb WiFi doogle does not work anymore. The configuration which was working
Doogle on PC A with 2 ethernet cards. One connected to PC B: a laptop one connected to PC C
Now, The laptop PC B is connect to a wifi mobile. It works wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.43.115 netmask 255.255.255.0 broadcast 192.168.43.255
I set the ethernet interface "shared to other computers" enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
Now I am trying to connect this ethernet card to PC A From the network interface, It tried "shared to other computers" and "Automatic (DHCP)", but none of them allow me to make the connection (connecting for ever). Hence, I tried manually 10.42.0.5 255.255.255.0 It connected enp1s0 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.5 netmask 255.255.255.0 broadcast 10.42.0.255
But the 2 computers do not talk together From PC B to PC A: ping 10.42.0.5 PING 10.42.0.5 (10.42.0.5) 56(84) bytes of data. From 10.42.0.1 icmp_seq=1 Destination Host Unreachable traceroute to 10.42.0.5 (10.42.0.5), 30 hops max, 60 byte packets 1 Sappho (10.42.0.1) 3068.823 ms !H 3068.691 ms !H 3068.614 ms !H route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.43.1 0.0.0.0 UG 600 0 0 wlp2s0 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enp3s0 192.168.43.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp2s0
From PC A to PC B: same behavior route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enpls0 192.168.122.0 0.0.0.0 255.255.255.0 U 600 0 0 virbr0
For now all my tests to connect to PC C failed.
I expect that I clarify the situation
Sent: Saturday, March 01, 2025 at 10:38 PM From: "Samuel Sieb" samuel@sieb.net To: users@lists.fedoraproject.org Subject: Re: internal network
On 3/1/25 7:03 AM, Patrick Dupre via users wrote:
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
What am I doing wrong?
Your description is very unclear. PC B is connected through a telephone??
Assuming it's actually a normal ethernet connection to the internet, PC B will need two ethernet cards. I don't understand how you have it connected right now.
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On Sat, 1 Mar 2025 at 22:22, Patrick Dupre via users < users@lists.fedoraproject.org> wrote:
I am lost.
I had a configuration with was working, but my usb WiFi doogle does not work anymore. The configuration which was working
Doogle on PC A with 2 ethernet cards. One connected to PC B: a laptop one connected to PC C
Now, The laptop PC B is connect to a wifi mobile. It works wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.43.115 netmask 255.255.255.0 broadcast 192.168.43.255
I set the ethernet interface "shared to other computers" enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
Now I am trying to connect this ethernet card to PC A From the network interface, It tried "shared to other computers" and "Automatic (DHCP)", but none of them allow me to make the connection (connecting for ever). Hence, I tried manually 10.42.0.5 255.255.255.0 It connected enp1s0 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.5 netmask 255.255.255.0 broadcast 10.42.0.255
But the 2 computers do not talk together From PC B to PC A: ping 10.42.0.5 PING 10.42.0.5 (10.42.0.5) 56(84) bytes of data. From 10.42.0.1 icmp_seq=1 Destination Host Unreachable traceroute to 10.42.0.5 (10.42.0.5), 30 hops max, 60 byte packets 1 Sappho (10.42.0.1) 3068.823 ms !H 3068.691 ms !H 3068.614 ms !H route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.43.1 0.0.0.0 UG 600 0 0 wlp2s0 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enp3s0 192.168.43.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp2s0
From PC A to PC B: same behavior route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enpls0 192.168.122.0 0.0.0.0 255.255.255.0 U 600 0 0 virbr0
I think if I'm reading your description correctly, this is roughly your topology and addressing?
https://photos.app.goo.gl/sWCqtQNNBBzBuGWk9
If my understanding is correct - the default gateway (0.0.0.0) from PC A (10.42.0.5) needs to be PC B (10.42.0.1) - you probably don't want 192.168.0.122.0 to be a gateway configured on PC A - you probably need ip_forwarding (net.ipv4.ip_forward) enabled on PC B if it's being used as an ersatz router
On 3/1/25 4:18 PM, Will McDonald wrote:
On Sat, 1 Mar 2025 at 22:22, Patrick Dupre via users <users@lists.fedoraproject.org mailto:users@lists.fedoraproject.org> wrote:
I am lost. I had a configuration with was working, but my usb WiFi doogle does not work anymore. The configuration which was working Doogle on PC A with 2 ethernet cards. One connected to PC B: a laptop one connected to PC C Now, The laptop PC B is connect to a wifi mobile. It works wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.43.115 netmask 255.255.255.0 broadcast 192.168.43.255 I set the ethernet interface "shared to other computers" enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255 Now I am trying to connect this ethernet card to PC A >From the network interface, It tried "shared to other computers" and "Automatic (DHCP)", but none of them allow me to make the connection (connecting for ever). Hence, I tried manually 10.42.0.5 255.255.255.0 It connected enp1s0 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.5 netmask 255.255.255.0 broadcast 10.42.0.255 But the 2 computers do not talk together >From PC B to PC A: ping 10.42.0.5 PING 10.42.0.5 (10.42.0.5) 56(84) bytes of data. >From 10.42.0.1 icmp_seq=1 Destination Host Unreachable traceroute to 10.42.0.5 (10.42.0.5), 30 hops max, 60 byte packets 1 Sappho (10.42.0.1) 3068.823 ms !H 3068.691 ms !H 3068.614 ms !H route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.43.1 0.0.0.0 UG 600 0 0 wlp2s0 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enp3s0 192.168.43.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp2s0 >From PC A to PC B: same behavior route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enpls0 192.168.122.0 0.0.0.0 255.255.255.0 U 600 0 0 virbr0I think if I'm reading your description correctly, this is roughly your topology and addressing?
https://photos.app.goo.gl/sWCqtQNNBBzBuGWk9 <https://photos.app.goo.gl/ sWCqtQNNBBzBuGWk9>
If my understanding is correct
- the default gateway (0.0.0.0) from PC A (10.42.0.5) needs to be PC B
(10.42.0.1)
Yes, DHCP should be working which would set the gateway, but he manually configured it and probably didn't put the gateway. Even without the gateway, the ping should have worked.
- you probably don't want 192.168.0.122.0 to be a gateway configured on PC A
That's not a gateway. That's the VM bridge interface with no gateway.
- you probably need ip_forwarding (net.ipv4.ip_forward) enabled on PC B
if it's being used as an ersatz router
That should have already been set by using the sharing option.
On Sat, 2025-03-01 at 16:03 +0100, Patrick Dupre via users wrote:
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP
If you mean that you enabled that in network manager, that means that A will be assigned an IP from a DHCP server. You need something on your LAN that does that job (acts as a DHCP server). It doesn't mean that becomes some kind of router sharing your internet.
If you meant that you're running a DHCP server on A, that would be odd as B seems to be your gateway.
But with a small LAN like yours, you might find it easier to just set manual IPs on all your PCs.
and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
On Sat, 2025-03-01 at 23:22 +0100, Patrick Dupre via users wrote:
I had a configuration with was working, but my usb WiFi doogle does not work anymore.
Replacing it isn't an option?
As for the best way forward... It might be worth letting us know if you were using a mix of cabled ethernet and WiFi because that's what you want to do, or just because you managed to get things working that way before.
The simplest solution for a small LAN is usually some kind of router with WiFi connected to your internet service, and everything connected to that in whatever way's convenient (cabled or WiFi). Often it is the device that connects to your internet, or it might sit after it.
ISP | router / \ PC PC (cabled or wireless connections)
The configuration which was working
Doogle on PC A with 2 ethernet cards. One connected to PC B: a laptop one connected to PC C
Now, The laptop PC B is connect to a wifi mobile. It works wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.43.115 netmask 255.255.255.0 broadcast 192.168.43.255
I set the ethernet interface "shared to other computers" enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
Now I am trying to connect this ethernet card to PC A From the network interface, It tried "shared to other computers" and "Automatic (DHCP)", but none of them allow me to make the connection (connecting for ever).
Sharing a connection *should* set up what you need for that PC to act as your router.
That DHCP setting expects some DHCP server on your LAN to configure that interface for you. If you don't have one, then use manual configuration of your network settings. For what you're doing, with just three devices, manual setting is probably easier to manage (on every device, set the interfaces you're using with the IPs you want).
You seem to have:
WiFi mobile 192.168.43.1 | | 192.168.43.115 PC B (acting as a gateway) 10.42.0.1 | | 10.42.0.5 PC A
PC A will need to have PC B (10.42.0.1) configured as its gateway address.
And PC B will need to have the WiFi mobile (192.168.43.1) as its gateway address for the 192.168.43.115 interface. "Sharing" out its 10.42.0.1 interface ought to set up internal networking properly.
This is where things get confusing... On some PC systems you would be sharing the internet connection (turning PC B into a router between the 192.168/16 and 10.42/16 networks). On others sharing seems to define which interface faces the LAN.
I used to do this around 20 years ago with dial-up internet (like the above sketch, but with a public IP on the outside face of B). This was pre-NetworkManager days, and I used a script to set up my networking, setting up a IP forwarding flag and firewall rules.
As for pinging between A & B not working... Firewall rules? Cross- over ethernet cable (I know they're *rarely* required these days).
Hence, I tried manually 10.42.0.5 255.255.255.0 It connected enp1s0 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 10.42.0.5 netmask 255.255.255.0 broadcast 10.42.0.255
But the 2 computers do not talk together From PC B to PC A: ping 10.42.0.5 PING 10.42.0.5 (10.42.0.5) 56(84) bytes of data. From 10.42.0.1 icmp_seq=1 Destination Host Unreachable traceroute to 10.42.0.5 (10.42.0.5), 30 hops max, 60 byte packets 1 Sappho (10.42.0.1) 3068.823 ms !H 3068.691 ms !H 3068.614 ms !H route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.43.1 0.0.0.0 UG 600 0 0 wlp2s0 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enp3s0 192.168.43.0 0.0.0.0 255.255.255.0 U 600 0 0 wlp2s0
From PC A to PC B: same behavior route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.42.0.0 0.0.0.0 255.255.255.0 U 100 0 0 enpls0 192.168.122.0 0.0.0.0 255.255.255.0 U 600 0 0 virbr0
For now all my tests to connect to PC C failed.
On Sun, 2 Mar 2025 at 09:12, Patrick Dupre pdupre@gmx.com wrote:
I set the gateway and now it works.
Now
- I wish to use internet from PC A.
I guess that I need to set a name server But not possible manually
nmcli connection modify <connection_name> ipv4.dns <dns_servers> (From: https://idroot.us/fedora-41-network-configuration/)
- How do I need to set for PC 3
From PC A From PC C I tried several things but none works
Your life would be made a lot simpler if you had a small switch or router, as Tim suggested. You can even get USB-powered devices.
Failing that: https://superuser.com/questions/1732698/two-interfaces-on-same-machine-with-...
On 2 Mar 2025, at 12:25, Will McDonald wmcdonald@gmail.com wrote:
Your life would be made a lot simpler if you had a small switch or router, as Tim suggested. You can even get USB-powered devices.
All the ISP modems I have ever seen have a 3 or 4 port switch built in.
Doesn't yours?
Barry
Patrick Dupre:
Yes the schamatics is correct. I set the gateway and now it works.
Now
- I wish to use internet from PC A.
I guess that I need to set a name server But not possible manually
Presuming that you just mean for using the internet... If internet sharing is working, then tell A to use the same name server that is working on B.
- How do I need to set for PC 3
From PC A From PC C I tried several things but none works
PC 3? You're adding a third PC into this mixture?
If B was your gateway, and it had an extra spare ethernet port. Any other approach would become a Frankenstein's monster of a network.
--------- ------------- ----------
I am currently horsing around with a Frankenetwork at the moment, somewhat similar to yours, thanks to my Fibre-to-the-house ISP becoming greedy and my dropping them. Likewise it's a temporary thing, though saving $60 to $80 a month is looking good, right now.
I have a mobile phone which can act as a wireless access point, and various devices around my house are using it as one. I only had to switch on Mobile Hotspot on the phone for it to act that way. I set its SSID to be the same as my former network, and the WiFi devices around the house are happy.
And I plug a desktop PC into the phone's USB port. I only had to switch on USB tethering on the phone, and the (ye olde CentOS) PC figured out what to do by itself, likewise if I do that with a Fedora PC, but an old Mac flatly refuses to do that (the phone is Android, and Apple are deliberately obstinate on not co-operating with non-Apple).
Things mostly work fine, apart from being double-natted (the phone and the phone service provider), and that's only one PC at a time.
The hard parts about doing this, are:
* The phone only supports up to 10 devices going through it (and there were more than 10 gadgets on my former wireless LAN).
* The phone service provider uses CGNAT (so I can't FTP into things).
* There's several non-WiFi devices, and my ye old CentOS server doesn't want to share the phone's internet service out its ethernet connection.
* All the desktop devices are still ethernet cabled together, so LAN work still works, but connecting the phone to one of them takes over from my DNS server and uses the phone as the DNS server sometimes and sometimes not. So you get either no local name resolution or no internet name resolution, until I fiddle with disconnecting and reconnecting things via desktop manager.
Dunno why my server doesn't want to co-operate with internet sharing, I've done that kind of thing before (with dial-up modem on the serial port). I settled for running Squid on that box, and the other computers can browse the net using it as a HTTP proxy.
But this kind of thing is messy and fragile (and temporary). Life's much easier with a proper internet service going into a router. WiFi and ethernet routers are quite cheap, now, probably on a par with a WiFi dongle. In my case, all I have to do is find a new ISP that I'm happy with (acceptable pricing and service levels, with a proper real public IP, and preferably FTTP not 5G).
We wouldn't have this no-public-IP problem if everyone had got their act together and set up IPv6 properly. But our ISPs would rather faff around with *very* limited CGNAT (my router used NAT, and I could always FTP through that without having to do anything special). My former ISP had IPv6 when I first joined, then a couple of months in they removed it, and remotely reconfigured the supplied modem/router combo to disable it.
hey Tim.
saw your post. could u let us know who the offending is is so we can avoid if possible!!
On Sun, Mar 2, 2025, 9:50 AM Tim via users users@lists.fedoraproject.org wrote:
Patrick Dupre:
Yes the schamatics is correct. I set the gateway and now it works.
Now
- I wish to use internet from PC A.
I guess that I need to set a name server But not possible manually
Presuming that you just mean for using the internet... If internet sharing is working, then tell A to use the same name server that is working on B.
- How do I need to set for PC 3
From PC A From PC C I tried several things but none works
PC 3? You're adding a third PC into this mixture?
If B was your gateway, and it had an extra spare ethernet port. Any other approach would become a Frankenstein's monster of a network.
--------- ------------- ----------I am currently horsing around with a Frankenetwork at the moment, somewhat similar to yours, thanks to my Fibre-to-the-house ISP becoming greedy and my dropping them. Likewise it's a temporary thing, though saving $60 to $80 a month is looking good, right now.
I have a mobile phone which can act as a wireless access point, and various devices around my house are using it as one. I only had to switch on Mobile Hotspot on the phone for it to act that way. I set its SSID to be the same as my former network, and the WiFi devices around the house are happy.
And I plug a desktop PC into the phone's USB port. I only had to switch on USB tethering on the phone, and the (ye olde CentOS) PC figured out what to do by itself, likewise if I do that with a Fedora PC, but an old Mac flatly refuses to do that (the phone is Android, and Apple are deliberately obstinate on not co-operating with non-Apple).
Things mostly work fine, apart from being double-natted (the phone and the phone service provider), and that's only one PC at a time.
The hard parts about doing this, are:
The phone only supports up to 10 devices going through it (and there were more than 10 gadgets on my former wireless LAN).
The phone service provider uses CGNAT (so I can't FTP into things).
There's several non-WiFi devices, and my ye old CentOS server doesn't want to share the phone's internet service out its ethernet connection.
All the desktop devices are still ethernet cabled together, so LAN work still works, but connecting the phone to one of them takes over from my DNS server and uses the phone as the DNS server sometimes and sometimes not. So you get either no local name resolution or no internet name resolution, until I fiddle with disconnecting and reconnecting things via desktop manager.
Dunno why my server doesn't want to co-operate with internet sharing, I've done that kind of thing before (with dial-up modem on the serial port). I settled for running Squid on that box, and the other computers can browse the net using it as a HTTP proxy.
But this kind of thing is messy and fragile (and temporary). Life's much easier with a proper internet service going into a router. WiFi and ethernet routers are quite cheap, now, probably on a par with a WiFi dongle. In my case, all I have to do is find a new ISP that I'm happy with (acceptable pricing and service levels, with a proper real public IP, and preferably FTTP not 5G).
We wouldn't have this no-public-IP problem if everyone had got their act together and set up IPv6 properly. But our ISPs would rather faff around with *very* limited CGNAT (my router used NAT, and I could always FTP through that without having to do anything special). My former ISP had IPv6 when I first joined, then a couple of months in they removed it, and remotely reconfigured the supplied modem/router combo to disable it.
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On Sun, 2025-03-02 at 09:58 -0500, bruce wrote:
hey Tim.
saw your post. could u let us know who the offending is is so we can avoid if possible!!
Hi Bruce,
My fired FTTP ISP was Telstra (Australia's service from hell), that thinks it's a premium service provider despite having outsourced everything. And who's answer to all the technical faults that *they* have is for you to reboot your system.
The mobile service using CGNAT is Vodafone (I gather it's not doing that nationwide, or wasn't). It does actually have IPv6, but I don't know if they're playing silly NAT games with it, too.
Trying to add a nameserver.
On PC B, I have Global Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub
Link 2 (enp3s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 3 (wlp2s0) Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6 Protocols: +DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 192.168.43.1 DNS Servers: 192.168.43.1
On PC A
Global Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub
Link 2 (enp1s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 3 (enp2s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 4 (virbr0) Current Scopes: none Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
What should I set on this PC A?
resolvectl dns enps2s0 192.168.43.1 systemctl restart systemd-resolved
Yes the schamatics is correct. I set the gateway and now it works.
Now
- I wish to use internet from PC A.
I guess that I need to set a name server But not possible manually
Presuming that you just mean for using the internet... If internet sharing is working, then tell A to use the same name server that is working on B.
- How do I need to set for PC 3
From PC A From PC C I tried several things but none works
PC 3? You're adding a third PC into this mixture?
If B was your gateway, and it had an extra spare ethernet port. Any other approach would become a Frankenstein's monster of a network.
--------- ------------- ----------I am currently horsing around with a Frankenetwork at the moment, somewhat similar to yours, thanks to my Fibre-to-the-house ISP becoming greedy and my dropping them. Likewise it's a temporary thing, though saving $60 to $80 a month is looking good, right now.
I have a mobile phone which can act as a wireless access point, and various devices around my house are using it as one. I only had to switch on Mobile Hotspot on the phone for it to act that way. I set its SSID to be the same as my former network, and the WiFi devices around the house are happy.
And I plug a desktop PC into the phone's USB port. I only had to switch on USB tethering on the phone, and the (ye olde CentOS) PC figured out what to do by itself, likewise if I do that with a Fedora PC, but an old Mac flatly refuses to do that (the phone is Android, and Apple are deliberately obstinate on not co-operating with non-Apple).
Things mostly work fine, apart from being double-natted (the phone and the phone service provider), and that's only one PC at a time.
The hard parts about doing this, are:
The phone only supports up to 10 devices going through it (and there were more than 10 gadgets on my former wireless LAN).
The phone service provider uses CGNAT (so I can't FTP into things).
There's several non-WiFi devices, and my ye old CentOS server doesn't want to share the phone's internet service out its ethernet connection.
All the desktop devices are still ethernet cabled together, so LAN work still works, but connecting the phone to one of them takes over from my DNS server and uses the phone as the DNS server sometimes and sometimes not. So you get either no local name resolution or no internet name resolution, until I fiddle with disconnecting and reconnecting things via desktop manager.
Dunno why my server doesn't want to co-operate with internet sharing, I've done that kind of thing before (with dial-up modem on the serial port). I settled for running Squid on that box, and the other computers can browse the net using it as a HTTP proxy.
But this kind of thing is messy and fragile (and temporary). Life's much easier with a proper internet service going into a router. WiFi and ethernet routers are quite cheap, now, probably on a par with a WiFi dongle. In my case, all I have to do is find a new ISP that I'm happy with (acceptable pricing and service levels, with a proper real public IP, and preferably FTTP not 5G).
We wouldn't have this no-public-IP problem if everyone had got their act together and set up IPv6 properly. But our ISPs would rather faff around with *very* limited CGNAT (my router used NAT, and I could always FTP through that without having to do anything special). My former ISP had IPv6 when I first joined, then a couple of months in they removed it, and remotely reconfigured the supplied modem/router combo to disable it.
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On 3/1/25 7:03 AM, Patrick Dupre via users wrote:
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
I just tested this setup and it works with no problem. I don't have wifi on the desktop, just two ethernet ports, but it should be the same. One ethernet port goes to "the internet" (internal network, but same). The other ethernet port I configured in the Gnome network manager as "shared to other computers". I then plugged a laptop into that ethernet port and it had internet access. So I'm not sure where you went wrong.
For PC C to have access, you have a couple of options. You could configure the two ethernet ports on PC A as a bridge or you could again configure the second ethernet port as shared.
On Sun, 2025-03-02 at 20:38 +0100, Patrick Dupre via users wrote:
Trying to add a nameserver.
On PC B, I have Global Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub
Link 2 (enp3s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 3 (wlp2s0) Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6 Protocols: +DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 192.168.43.1 DNS Servers: 192.168.43.1
On PC A
Global Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub
Link 2 (enp1s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 3 (enp2s0) Current Scopes: LLMNR/IPv4 LLMNR/IPv6 Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
Link 4 (virbr0) Current Scopes: none Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
What should I set on this PC A?
resolvectl dns enps2s0 192.168.43.1 systemctl restart systemd-resolved
With what we're presuming to be your network topology, and the usual way things are done when sharing an internet connection, and presuming you just want a DNS server that lets everyone surf the internet rather than be a resolver of local addresses:
WiFi mobile 192.168.43.1 | | 192.168.43.115 PC B (acting as a gateway) 10.42.0.1 | | 10.42.0.5 PC A
B should be using the 192.168.43.1 device as its DNS server, and A should be using B (10.42.0.1) as its DNS server. B should be behaving like some kind of forwarder for the name resolution requests (either acting as a kind of proxy, answering them itself, or just redirecting IP packets through to the mobile device and using it as the DNS server).
And it might be worth having a look at this:
https://fedoramagazine.org/internet-connection-sharing-networkmanager/
It's a bit old, but might say something helpful.
Connection between A and B work fine.
The only think that I cannot build is the connection with PC C (I manually set up the ip address, etc..) What do you mean by
You could configure the two ethernet ports on PC A as a bridge or you could again configure the second ethernet port as shared.
Is bridge synonymy of "shared to other computers"? If yes, every time that I do that, it generates an address in 10.40.0.1 while this address has been on PC B. On PC A, I set the card wired to PC B manually to 10.42.0.2 with a gateway 10.42.0.1 (the interface shared on PC A). This works fine. The second interface on PC A (wired to PC C), set it to 10.42.0.3 I tried without a gateway and with gateway 10.42.0.2 (and 10.42.0.1) On PC C, I set (manually) the IP 10.42.0.5, with a gateway 10.42.0.2 or 10.42.0.3. THis does not work.
On 3/1/25 7:03 AM, Patrick Dupre via users wrote:
I have 2 PC A and B. Before A what connected to the world wireless and PC B was connected through an internet cable (wired). PC A lost its wireless connection. Now PC B is connected to the world through a telephone and I want to have PC A connected also through the same internet cable and access to the world.
On PC A I activated Automatic DHCP and on PC B and the internet card 10.42.0.1 shared to other computers (IP) It connects inet 10.42.0.1 netmask 255.255.255.0 broadcast 10.42.0.255
but PC B cannot connect (connection fails)
I just tested this setup and it works with no problem. I don't have wifi on the desktop, just two ethernet ports, but it should be the same. One ethernet port goes to "the internet" (internal network, but same). The other ethernet port I configured in the Gnome network manager as "shared to other computers". I then plugged a laptop into that ethernet port and it had internet access. So I'm not sure where you went wrong.
For PC C to have access, you have a couple of options. You could configure the two ethernet ports on PC A as a bridge or you could again configure the second ethernet port as shared.
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On Mon, 2025-03-03 at 12:30 +0100, Patrick Dupre via users wrote:
Is bridge synonymy of "shared to other computers"?
No, it's more of a straight through (or over, hence the name). Or, you might think of it as a pass-through.
If yes, every time that I do that, it generates an address in 10.40.0.1 while this address has been on PC B. On PC A, I set the card wired to PC B manually to 10.42.0.2 with a gateway 10.42.0.1 (the interface shared on PC A). This works fine. The second interface on PC A (wired to PC C), set it to 10.42.0.3 I tried without a gateway and with gateway 10.42.0.2 (and 10.42.0.1) On PC C, I set (manually) the IP 10.42.0.5, with a gateway 10.42.0.2 or 10.42.0.3. THis does not work.
Your second PC in the middle is your problem.
I'm wondering *how* you have two ethernet ports on some computers. Are they plug-in cards? If so, you'd probably be best to unplug one and put it into your gateway PC, giving it three ethernet ports, giving this kind of network topology:
internet service | B / \ A C
B is the gateway, and only PC you have to specially configure to make things work.
You seem to be daisy-chaining one PC through another, through another. This is NOT an easy thing to do well. With this kind of thing:
internet service 192.168.43.1 | | 192.168.43.115 PC B 10.42.0.1 | | 10.42.0.5 PC A 172.16.0.5 | | 172.16.0.3 PC C
The networks on either side of B have different subnets, and B acts as a router between them. We've already been through that.
Now, A needs to do the same kind of thing, being a router between it and C. And either side of it be on a different subnet, to do that. *AND* B and A both have to manage to handle getting things between C and B, and the internet. That's the really tricky bit! Depending on how NAT is programmed (internally, not just your configuration), it may not have the smarts to get things from C to B, or C to the internet.
I'm throwing in a different subnet numerical IP addresses into that example to strongly illustrate the idea that (normally) networks facing each other are in the same network families, and networks on the other side of a boundary are (normally) from a different family.
Not that you need to be that extreme in different networking IPs to use. You could use the 10.x.y.z scheme with 10.1/16 in one portion, 10.2/16 in the next portion, and 10.3/16 in the final portion. I'm just trying to make the example very clear.
Router's use the difference between the netmasked portion of an IP address to see what's the same, and what's not, to decide what packets that they have to redirect through themselves to a new destination. And packets with similar addresses (on the same network as each other) just directly communicate with each other on the same side.
WiFi connections add another potential problem to resolve: Whether your WiFi router allows WiFi devices to interact, or it walls everything off from each other.
On the other hand, if you simply had a switch between your internet service and the rest of your network, they'd all be on the same IP networks and interacting with each other without you having to do anything special. Your internet service device would be handling all the hard work for you.
internet service 192.168.43.1 | ethernet switch device / | \ PC A PC B PC C 192.168.43.2 192.168.43.3 192.168.43.4
And that's how my home LAN was wired for over the last decade. In my case the "internet service" was a combined ethernet and WiFi router. And was somewhat more like this:
internet service their public IP (assigned by my ISP) | | my public IP (assigned by my ISP) my ethernet & WiFi router 192.168.1.254 WiFi--- 192.168.1.6 (phone) | \ \ | \ 192.168.1.5 (tablet) ethernet switch with more \ ports than my router has 192.168.1.4 / | \ smart TV / | \ 192.168.1.1 192.168.1.2 192.168.1.3 A PC another PC laptop
All the hard work of getting the network to net*WORK* is done by the router, all my devices are simply connected to it without any special network configuration being necessary on them.
And since your internet service is using a private LAN IP (192.168/16) rather than a public IP, you ought to be able to do the same kind of networking without any problems.
Network switches are cheap, and have zero configuration. Just plug everything in together.
On Mon, 2025-03-03 at 12:30 +0100, Patrick Dupre via users wrote:
Is bridge synonymy of "shared to other computers"?
No, it's more of a straight through (or over, hence the name). Or, you might think of it as a pass-through.
If yes, every time that I do that, it generates an address in 10.40.0.1 while this address has been on PC B. On PC A, I set the card wired to PC B manually to 10.42.0.2 with a gateway 10.42.0.1 (the interface shared on PC A). This works fine. The second interface on PC A (wired to PC C), set it to 10.42.0.3 I tried without a gateway and with gateway 10.42.0.2 (and 10.42.0.1) On PC C, I set (manually) the IP 10.42.0.5, with a gateway 10.42.0.2 or 10.42.0.3. THis does not work.
Your second PC in the middle is your problem.
I'm wondering *how* you have two ethernet ports on some computers. Are they plug-in cards? If so, you'd probably be best to unplug one and put it into your gateway PC, giving it three ethernet ports, giving this kind of network topology:
On PC A and PC C, the ethernet car is actually on the mother board. On PC B, one ethernet port is on the mother board, the other one is plugeed in the PCI bus.
internet service | B / \ A C
This was the omder configuration. It was working as a charm. Now B is a laptop, and I have only one ethernet port. HEnce I have to wire PC C to PC B which has 2 ethernet ports.
B is the gateway, and only PC you have to specially configure to make things work.
You seem to be daisy-chaining one PC through another, through another. This is NOT an easy thing to do well. With this kind of thing:
internet service 192.168.43.1 | | 192.168.43.115 PC B 10.42.0.1 | | 10.42.0.5 PC A 172.16.0.5 | | 172.16.0.3 PC C
The networks on either side of B have different subnets, and B acts as a router between them. We've already been through that.
Now, A needs to do the same kind of thing, being a router between it and C. And either side of it be on a different subnet, to do that. *AND* B and A both have to manage to handle getting things between C and B, and the internet. That's the really tricky bit! Depending on how NAT is programmed (internally, not just your configuration), it may not have the smarts to get things from C to B, or C to the internet.
I'm throwing in a different subnet numerical IP addresses into that example to strongly illustrate the idea that (normally) networks facing each other are in the same network families, and networks on the other side of a boundary are (normally) from a different family.
Not that you need to be that extreme in different networking IPs to use. You could use the 10.x.y.z scheme with 10.1/16 in one portion, 10.2/16 in the next portion, and 10.3/16 in the final portion. I'm just trying to make the example very clear.
Router's use the difference between the netmasked portion of an IP address to see what's the same, and what's not, to decide what packets that they have to redirect through themselves to a new destination. And packets with similar addresses (on the same network as each other) just directly communicate with each other on the same side.
WiFi connections add another potential problem to resolve: Whether your WiFi router allows WiFi devices to interact, or it walls everything off from each other.
On the other hand, if you simply had a switch between your internet service and the rest of your network, they'd all be on the same IP networks and interacting with each other without you having to do anything special. Your internet service device would be handling all the hard work for you.
internet service 192.168.43.1 | ethernet switch device / | \PC A PC B PC C 192.168.43.2 192.168.43.3 192.168.43.4
And that's how my home LAN was wired for over the last decade. In my case the "internet service" was a combined ethernet and WiFi router. And was somewhat more like this:
internet service their public IP (assigned by my ISP) | | my public IP (assigned by my ISP) my ethernet & WiFi router 192.168.1.254 WiFi--- 192.168.1.6 (phone) | \ \ | \ 192.168.1.5 (tablet) ethernet switch with more \ ports than my router has 192.168.1.4 / | \ smart TV / | \192.168.1.1 192.168.1.2 192.168.1.3 A PC another PC laptop
All the hard work of getting the network to net*WORK* is done by the router, all my devices are simply connected to it without any special network configuration being necessary on them.
And since your internet service is using a private LAN IP (192.168/16) rather than a public IP, you ought to be able to do the same kind of networking without any problems.
Network switches are cheap, and have zero configuration. Just plug everything in together.
Yes, this right. Again, it is a temporally configuration before I can go back the the previous configuration. Following your suggestion, I set the following
On PC A, the interface for PC C with IP 10.42.1.1 with a gateway to 10.42.0.2 and on PC C IP 10.42.1.2 with a gateway to 10.42.1.1
It let me communicate between PC A and PC C, But not between PC C and PC B. Would it be possible?
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On 3/3/25 3:30 AM, Patrick Dupre via users wrote:
Connection between A and B work fine.
The only think that I cannot build is the connection with PC C (I manually set up the ip address, etc..) What do you mean by
You could configure the two ethernet ports on PC A as a bridge or you could again configure the second ethernet port as shared.
Is bridge synonymy of "shared to other computers"? If yes, every time that I do that, it generates an address in 10.40.0.1 while this address has been on PC B. On PC A, I set the card wired to PC B manually to 10.42.0.2 with a gateway 10.42.0.1 (the interface shared on PC A). This works fine. The second interface on PC A (wired to PC C), set it to 10.42.0.3 I tried without a gateway and with gateway 10.42.0.2 (and 10.42.0.1) On PC C, I set (manually) the IP 10.42.0.5, with a gateway 10.42.0.2 or 10.42.0.3. THis does not work.
The issue is that the default subnet is always the same, so both computers are sharing the same subnet, which doesn't work. Here's an article that explains more about the sharing and how you can adjust the subnet: https://fedoramagazine.org/internet-connection-sharing-networkmanager/
On Mon, 2025-03-03 at 17:21 +0100, Patrick Dupre via users wrote:
Following your suggestion, I set the following
On PC A, the interface for PC C with IP 10.42.1.1 with a gateway to 10.42.0.2 and on PC C IP 10.42.1.2 with a gateway to 10.42.1.1
I am thoroughly confused by that description. The best I can guess is that you've done this:
internet 192.168.43.1 | | 192.168.43.115 PC B 10.42.0.1 | | 10.42.0.5 PC A 10.42.1.1 | | 10.42.1.2 PC C
It let me communicate between PC A and PC C, But not between PC C and PC B. Would it be possible?
internet service | B | A | C
Each PC has its gateway address set to the IP of the device immediately above it (the gateway is where non-local [not its own subnet] traffic goes through), and each PC shares its internet out its interface facing downwards.
B has its gateway address set to the internet service IP (above) facing B, B is sharing its internet out the downward facing interface, B acts as the router between what's below it to the internet, and routes any traffic that's not internal or LAN traffic out its gateway to the internet.
A has its gateway address set to B's IP facing A, A is sharing its internet out the downward facing interface, it will act as the router for C to B, routing any traffic that's not meant to go downward, upward (in that diagram) for itself and C.
C has its gateway address set to A's IP facing C, all traffic that isn't internal will go through its gateway (A) upwards.
Draw a diagram for yourself, fill in the addresses, picture the routing that has to be done. Make life easier for yourself, rather than confusing random-seeming IPs, make the digits of your IPs logically associated with your PC names.
A will have the hardest job of figuring out which direction to route things upwards or downwards. I'm not sure if B could talk to C without a fair bit of manual route configuration, too, C to B might be slightly easier. Probably the best you could hope for is can each PC browse the internet
In all seriousness, this is hard to manage correctly. And may not work depending on how well its NAT has been programmed (by the programmer, not just you). And may come to a grinding halt if the internet device loses connectivity, reacquires it, and nothing below it knew about what happened.
I'm not sure about this with Fedora, but with other systems I'd certainly be getting one device at the top of the chain up and running, then going down the chain one by one. I don't just mean doing the configuration, I mean starting the network in a sequence. It is a house of cards.
In the past I have tried doing what you are with a laptop, simply for the sake of trying it, on an otherwise fully functional network. It did not go well.
As you're double-NATing (or triple NATing, considering the mobile internet device is also NATing), traffic will be fragile. And you will have to manually reconfigure how A does its NAT for it to use completely different IPs than what NAT is doing on B. This is more than just manually configuring IPs for your interfaces, it's also configuring IPs in NAT configuration.
You would be far better to swap a couple of computers around and have just one gateway in the middle without all the daisy-chaining.
This kind of (family tree) NATing is painful enough:
internet / | \ router--router--router / | \ | \ / | \ PC PC PC PC PC PC PC PC
It's logical, and well within the abilities of NAT. Often, used to deliberately isolate subnets from each other in large organisations, with some very carefully configured interlinking for a few specific things (such as mail servers). But that interlinking requires careful consideration, and it's designed with minimal PC to PC communication allowed.
I wouldn't attempt daisy chaining like you are doing.
What is daisy-chaining? Multi-drop bus (each device connected to a common wire)? Forwarding (each device has two distinct connections)? Something else?
Discovering the topology was easy. Details, not so much.
On Thu, 2025-03-06 at 19:42 -0600, Michael Hennebry wrote:
What is daisy-chaining?
Named after making a necklace from intertwining daisies together, it's one thing connected to another, to another through another, to another through another, etc.
Internet <--> PC <--> PC <--> PC
On 3/2/25 8:10 AM, Barry Scott wrote:
On 2 Mar 2025, at 12:25, Will McDonald wmcdonald@gmail.com wrote:
Your life would be made a lot simpler if you had a small switch or router, as Tim suggested. You can even get USB-powered devices.
All the ISP modems I have ever seen have a 3 or 4 port switch built in.
Doesn't yours?
Barry
The Spectrum modem only has oneport. It would only connect to their proprietary router with an extra monthly charge not my Reyee.
On Sun, 2025-03-09 at 16:51 -0400, Robert McBroom via users wrote:
The Spectrum modem only has oneport. It would only connect to their proprietary router with an extra monthly charge not my Reyee.
If a PC can connect to it, so can a router.
They may require you to connect something to it so that they can authorise its MAC address. But if you can connect any of your PCs to it, and they work, and you haven't had to have them authorise it, then that shouldn't be the case.
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Barry Scott -
bruce -
Michael Hennebry -
Patrick Dupre -
Robert McBroom -
Samuel Sieb -
Tim -
Will McDonald