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 ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital ricks@xxxxxxxxxxxxxx - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - - Huked on foniks reely wurked for me! - ---------------------------------------------------------------------- _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
