# resolution problem for single hosts reachable elsewhere

## fangorn

Hi,

I have a strange problem that is beyond my understanding of the TCP/IP commúnication. 

I am running a personal video recorder that is running SABNZB as download manager 

for UseNet data. After a fresh start it runs for some days without problems. Then SABNZB

looses connection to the server ("no route to host"). Finally even ping is not able to reach 

the server any more. SABNZB uses SSL connections. I have not tested if unencrypted 

connections have the same effect. The whole time resolution and routing for other 

hosts stays intact. 

The whole time the server is reachable from another machine using the same Gateway. 

From ping and SABNZB using the same settings. The hostname gets resolved to the IP 

adress without problems. The connection attempt just does not leave the machine. 

```
-> traceroute news-europe.giganews.com

traceroute to news-europe.giganews.com (216.196.109.144), 30 hops max, 60 byte packets

 1  kankra.mittelerde.zz (192.168.0.1)  3002.399 ms !H  3002.394 ms !H  3002.383 ms !H
```

"ip route" does not show any additional routing entries that could interfere with this special

host. 

The setting - whatever it is - is temporal, after reboot the routing works again. But as this is

a PVR and fileserver I cannot just reboot the machine whenever the host is not reachable 

any more. 

Does this have something to do with the ARP table? Or does someone have an idea what might

be the cause of this? I just replaced a years old installation of mythbuntu with Gentoo on 

this machine. I never had this problem on Mythbuntu. So maybe I just did miss a setting. 

This is my full network setting: 

```
config_eth0=( "192.168.0.1 netmask 255.255.255.0 brd 192.168.0.255" )

routes_eth0=( "default via 192.168.0.13" )

dns_domain_eth0=( "mittelerde.zz" )

dns_servers_eth0=( "192.168.0.13" )
```

This is a little out of my league. Maybe someone of the professional networkers knows this problem. 

fangorn.

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## fangorn

The replacement machine has the same problem after some days. 

So it might be something missing from the kernel config. 

Here is the most recent kernel config in use. 

http://dump.fangornsrealm.eu/config_3.1.1-gentoo

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## fangorn

Or are there some limits for the number of connections?

i seem to remember that other usenet Clients had quite some stalled connections.

is there a way to allow more or reduce the time till the kernel automtically closes 

hajging connections?

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## fangorn

I definately have to look into this. I have now a virtual machine running on the PVR 

that is based on a minimal Debian installation and does just the Download with 

SABnzbd. It does not show any signs of network connection problems. 

It just is slow as hell with filesystem access because the storage is attached over 

NFS and the virtualbox network driver.  :Rolling Eyes: 

No idea where I can start searching?

----------

