I have two hosts in my network. Both are connected to my router. From another host, I can ping and ssh into both of them. Both have an excellent connection to all other hosts. However, they cannot ping or see one another. One (192.168.124.101, called Hallway) runs Ubuntu 14.10, the other (192.168.124.104, called Rapunzel) is a Raspberry Pi with Raspbian. Both addresses are static. The hosts are connected to the electrical network through Powerline adapters.
jos@hallway:~$ ifconfig eth1 eth1 Link encap:Ethernet HWaddr 00:14:85:82:2a:2f inet addr:192.168.124.101 Bcast:192.168.124.255 Mask:255.255.255.0 inet6 addr: fe80::214:85ff:fe82:2a2f/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2959658 errors:0 dropped:91 overruns:0 frame:0 TX packets:2366877 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3406445368 (3.4 GB) TX bytes:964531766 (964.5 MB) Interrupt:21 jos@hallway:~$ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default Comtrend.Home 0.0.0.0 UG 0 0 0 eth1 192.168.124.0 * 255.255.255.0 U 0 0 0 eth1 jos@hallway:~$ arp -a 192.168.124.104 rapunzel (192.168.124.104) at b8:27:eb:a4:84:a3 [ether] PERM on eth1
and vice versa:
pi@Rapunzel ~ $ ifconfig eth0 eth0 Link encap:Ethernet HWaddr b8:27:eb:a4:84:a3 inet addr:192.168.124.104 Bcast:192.168.124.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:60981 errors:0 dropped:0 overruns:0 frame:0 TX packets:40710 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:19883333 (18.9 MiB) TX bytes:2562029 (2.4 MiB) pi@Rapunzel ~ $ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default Comtrend.Home 0.0.0.0 UG 0 0 0 eth0 192.168.124.0 * 255.255.255.0 U 0 0 0 eth0 pi@Rapunzel ~ $ arp -a 192.168.124.101 hallway (192.168.124.101) at 00:14:85:82:2a:2f [ether] on eth0
I have tried adding and deleting routes and arp entries. The current arp entries were added automatically, however (so there is some sort of contact). At first, a
ping on either side would mention that the other side was "Destination host unreachable". The arp entries would give "<incomplete>" as the MAC address. After the arp entries were added, the pings simply time out.
It is probably not a firewall problem, for I have never used iptables on either of these machines (
sudo iptables -L gives the default output on both hosts). I have rebooted both machines and the router, but so far nothing helps.
Things worked until yesterday, when I disconnected and reconnected one of the hosts. What am I overlooking?
Edit: I ran a
tcpdump arp from host 101, and sure enough, I got numerous requests like the following:
23:12:23.460191 ARP, Request who-has hallway tell rapunzel, length 46 23:12:23.460214 ARP, Reply hallway is-at 00:14:85:82:2a:2f (oui Unknown), length 28
So why does no other traffic get through?
I ran an arping probe from both sides:
jos@hallway:~arping -b -D -w 2000 -I eth1 -s 192.168.124.101 192.168.124.104 ARPING 192.168.124.104 from 192.168.124.101 eth1 ^CSent 38 probes (38 broadcast(s)) Received 0 response(s)
and something similar at the other end (only formatted differently, this is Raspbian after all).