I'm running a 14.04.2 LTS ubuntu box in a DMZ with IP of 10.10.30.35 and I have the following network mystery. I'm trying to connect to another unix box outside the DMZ but in our internal network at 10.2.0.200 (via ssh or https) and failing with errors like
No route to host or
ping brings Destination Host Unreachable. However, I can connect (ping, ssh, & https) to a similar unix box at 10.2.0.170 that is also outside the DMZ but inside our network. I have nothing in my iptables:
> iptables --list Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination
The gateway looks to be set up correctly:
> route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.10.30.25 0.0.0.0 UG 0 0 0 eth0 10.10.30.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
When I do a tcpdump from the machine in the DMZ and try to ping the 10.2.0.200 box, all I ever see is this:
ARP, Request who-has 10.2.0.200 tell myserver.mydomain.com, length 28
However, I never see any response or any other traffic to 10.2.0.200. So it looks like the arp protocol is not working? Checking arp, I get this:
> arp -na ? (outsideipaddress) at <incomplete> on eth0 ? (10.10.30.25) at 00:1a:8c:f0:50:82 [ether] on eth0 <-- gateway ? (10.10.30.80) at 00:50:56:a7:06:89 [ether] on eth0 ? (outsideipaddress) at <incomplete> on eth0 ? (10.2.0.200) at <incomplete> on eth0 ? (outsideipaddress) at <incomplete> on eth0
So, that 10.2.0.200 entry is odd, I try to clear it out and get this:
> arp -d 10.2.0.200 SIOCDARP(dontpub): Network is unreachable
Attempts to use
ip -s -s neigh flush all do not remove the entry either.
So, I am at my wits end here. Is it the arp entry that is preventing my connection to 10.2.0.200? Or something else I am missing altogether? Can I just manually edit the arp table somehow and add the MAC address?
Thanks in advance for your help.