Jul 29, 2010
I'm having an issue on two Fedora Core 13 machines where I can ping others by hostname, but the hostname resolution fails whenever I use ssh/scp/vnc/etc. I can still do these things by IP address, just not by hostname. RHEL5.3 machines on the same network with the same configuration do not seem to have this problem.
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Here's the not-so-quick-and-dirty description of the situation:
I know that there is a virtual router at 192.168.31.1 and another at 192.168.30.1. I also know that there is another network (let's call it 126.96.36.199) and on that network lies a number of resources. By nature of this configuration, any machine on 188.8.131.52 can be accessed by any 192.168.x.x, but not the other way around. Beyond that is out of my hands and currently out of my scope of knowledge.
I have a dnsmasq server on 184.108.40.206 that operates as a secondary nameserver, another machine out of my sphere of influence is the primary nameserver (220.127.116.11).
The secondary nameserver on 18.104.22.168 holds the hostnames of our development machines. The problem is that in some cases, while I can ping by hostname all day long, services such as ssh, scp, vncviewer, etc all fail to resolve the hostname. In other cases I can do all of these things.
Every machine has an equivalent resolv.conf:
As an example, I will show the output of a handful of my development machines:
I also included columbia as a one-way test -- even though it cannot access 30.x or 31.x, they can access it:
columbia -- physical machine, Red Hat Enterprise 5.3, IP 192.168.100.200
Okay, so here are the various outputs. Remember, nibbler, discovery, and atlantis can ALL:
- Ping by IP address
- Ping by hostname
- ssh, scp, vnc, etc by IP addess
Additionally, the SERVFAIL reply from 22.214.171.124 is expected since my dnsmasq server is on the secondary server.
Note that the only machine that can both ping and ssh/scp/etc by hostname is nibbler, which also happens to be the only one of the three running RHEL5.3 instead of FC13. Other virtual and physical machines running on the 192.168.31.0 and 192.168.30.0 networks (all running RHEL5.3) work just like nibbler does. So the problem seems to only affect machines running FC13.
Final note: selinux is disabled, iptables is disabled, ip6tables is disabled.
Other than that, discovery is a brand-spanking-new install straight off of the FC13 DVD. atlantis has been around longer, but its just a file server so I haven't done anything too crazy to it.