[Openswan Users] Unusual packet loss

Paul Wouters paul at xelerance.com
Mon Jan 24 12:07:25 CET 2005

On Mon, 24 Jan 2005, Philip Burrow wrote:

> To my point, I'm having an unusual problem with apparent packet loss across a 
> tunnel. Let me describe the set up. I have two machines running Fedora 2, 
> with 2.6.10 kernel and Openswan 2.3.0. Both are on ADSL connections with 256k 
> upstream operated by the same ISP.

Do you have the xfrm4_tunnel kernel module? If so, did you load it?

> Another example of strangeness is if I try and FTP across the tunnel. I can 
> log in and such, as expected, but it hangs when I request a directory 
> listing.

This definately seems like compression (xfrm4_tunnel needed) or mtu problems.

> Any suggestions as to what may be causing this? From what I read in the 
> documentation it looks like MTU may be involved but I don't see why it would 
> be, and don't know what I can do to play with it. Guidance would be 
> appreciated!

I assume you're usig NETKEY, so try changing the mtu to something lower on
both ends on the physical interface, eg ethX/pppX


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