scyld beowulf server problems

Jonathan Hutchins hutchins at tarcanfel.org
Wed Apr 16 14:42:00 CDT 2003


In most port forwarding environments I know of, there is a problem if a client 
inside the firewall tries to access an internal server using the IP or Name 
address of the firewall.  This has it's workarounds, including using a local 
DNS server for the name redirection.  There's also a convoluted method to be 
done on the firewall, but it's based on having a full Linux firewall to work 
with.

If I understand correctly, you have some means of reflecting an external 
connection back through the firewall to the server.  

You have confirmed that if you assign the IP address of the server to a 
different system (your laptop), the forwarding is working, correct?  This would 
imply that it isn't the firewall that's the problem, right?

I found I had to go in with crowbar and hammer and rip out IPTables/Chains and 
the various protections that were installed by default on one of the servers I 
built simply because I didn't want to have to enable everything on both 
firewall and server.  I suspect that something among the IP filtering on the 
server, xinetd settings, or possibly even your htconfig file is excluding non-
local address ranges.

One thing to check is to use netstat -a to view connections and see if 
something is actually connecting to the server, just failing to get a response.

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