On 02/24/2017 02:19 AM, Gary Stainburn 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
---------------------------------------------------
[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 ~]#
The most common issue with this sort of thing is ARP and/or route
confusion. You have a machine with two interfaces on the same network.
Try doing this as root on zeppo (the machine with two interfaces):
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
And try your pings again. If that solves your problem, add these lines
to your /etc/sysctl.conf file:
# needed for two NICs on the same network
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
That will make them effective on a reboot. If that doesn't fix your
issue, reset the values via:
echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce
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- Rick Stevens, Systems Engineer, AllDigital ricks(a)alldigital.com -
- AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 -
- -
- Huked on foniks reely wurked for me! -
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