On 24Feb2017 10:19, Gary Stainburn <gary.stainburn@xxxxxxxxxxxxxx> wrote:
Here's an odd one for you.
I have a Fedora 19 box - GROUCHO - that is the DNS/DHCP/email/...... server
for one of my LANs
On there I have a home-grown network status monitor which pings a list of IP's
and monitors the state, reporting anything that goes missing.
The IP address of this host is 10.6.1.1/24
I also have a Centos 7 box - ZEPPO - on the same subnet/VLAN. This box is a
file/print server.
This box has two IP addresses 10,6.1.3/24 and 10.6.1.101/24
Groucho happily pings Zeppo on the 10.6.1.101 address.
I have now added a USB WiFi dongle to Zeppo and configured it using nmtui.
This is to put Zeppo onto the WiFi and enable Air Printing from IPads.
All of this works perfectly fine, and no other devices have any issues -
except groucho.
If the WiFi link is up on Zeppo, Groucho cannot ping it. If the WiFi link is
down on Zeppo, Groucho can ping it. As I say, the WiFi link state doesn not
affect any other device, Linux or otherwise.
Neither device have firewalling enabled (for this testing) and both devices
have very simple routing tables. Even when Groucho cannot ping Zeppo, Zeppo
can still ping Groucho
Maybe you can draw us a tiny physical network diagram. It sounds to me like
your wifi and your LAN are not connected (eg via a switch). It is generally a
bad idea to had physically distinct networks with the _same_ network range.
Also, below, how does the output or "route -n" change on zeppo _after_ you
bring up the wifi?
I'm expecting that your _return_ pings from zeppo are going out over the wifi
where groucho does not see them.
Our wifi/wired network here looks like this:
isp<->fw<->switch<->airport<...>wifi-hosts
|
wired-hosts
an it is all one network. The switch and the airport (also effectively a
switch) pass packets back and forth on a layer 2 (MAC address) level.
We actually also have another network out another port on the firewall here; it
is separately numbered - a distinct network range.
Cheers,
Cameron Simpson <cs@xxxxxxxxxx>
---------------------------------------------------
[root@zeppo ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.6.1.254 0.0.0.0 UG 100 0 0 enp3s0
10.6.1.1 10.6.103.254 255.255.255.255 UGH 600 0 0
wlp0s26u1u2
10.6.1.3 0.0.0.0 255.255.255.255 UH 100 0 0 enp3s0
10.6.1.101 0.0.0.0 255.255.255.255 UH 100 0 0 enp3s0
10.6.1.254 0.0.0.0 255.255.255.255 UH 100 0 0 enp3s0
10.6.103.0 0.0.0.0 255.255.255.0 U 600 0 0
wlp0s26u1u2
[root@zeppo ~]# nmcli con up RW54254
Connection successfully activated (D-Bus active
path: /org/freedesktop/NetworkManager/ActiveConnection/2)
[root@zeppo ~]#
---------------------------------------------------
[root@groucho ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.6.1.254 0.0.0.0 UG 0 0 0 p4p1
10.6.1.0 0.0.0.0 255.255.255.0 U 1 0 0 p4p1
169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 p4p1
[root@groucho ~]# ping zeppo
PING zeppo.ringways.co.uk (10.6.1.101) 56(84) bytes of data.
From groucho.ringways.co.uk (10.6.1.1) icmp_seq=1 Destination Host Unreachable
From groucho.ringways.co.uk (10.6.1.1) icmp_seq=2 Destination Host Unreachable
From groucho.ringways.co.uk (10.6.1.1) icmp_seq=3 Destination Host Unreachable
From groucho.ringways.co.uk (10.6.1.1) icmp_seq=4 Destination Host Unreachable
^C
--- zeppo.ringways.co.uk ping statistics ---
5 packets transmitted, 0 received, +4 errors, 100% packet loss, time 4002ms
pipe 4
[root@groucho ~]#
---------------------------------------------------
[root@zeppo ~]# nmcli con down RW54254
Connection 'RW54254' successfully deactivated (D-Bus active
path: /org/freedesktop/NetworkManager/ActiveConnection/3)
[root@zeppo ~]#
---------------------------------------------------
[root@groucho ~]# ping zeppo
PING zeppo.ringways.co.uk (10.6.1.101) 56(84) bytes of data.
64 bytes from zeppo.ringways.co.uk (10.6.1.101): icmp_seq=1 ttl=63 time=0.230
ms
64 bytes from zeppo.ringways.co.uk (10.6.1.101): icmp_seq=2 ttl=63 time=0.228
ms
64 bytes from zeppo.ringways.co.uk (10.6.1.101): icmp_seq=3 ttl=63 time=0.229
ms
64 bytes from zeppo.ringways.co.uk (10.6.1.101): icmp_seq=4 ttl=63 time=0.213
ms
^C
--- zeppo.ringways.co.uk ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 2999ms
rtt min/avg/max/mdev = 0.213/0.225/0.230/0.007 ms
[root@groucho ~]#
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--
Cameron Simpson <cs@xxxxxxxxxx>
It is always preferable to visit home with a friend. Your parents will not
be pleased with this plan, because they want you all to themselves and
because in the presence of your friend, they will have to act like mature
human beings ... - Playboy, January 1983
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