router causing ssh etc. slowdown?

[Scot L. Harris]

On Mon, 2004-10-25 at 04:23, Stewart Nelson wrote:

> > My gripe comes when I try to SSH to my FC2 box from my laptop, going 
> > through the Internet (ssh <external-router-ip>)
> 
> Most NAT routers don't work properly when you connect to a (forwarded)
> port on their public IP from a host on their own LAN.
> 
Would like to understand which NAT routers don't work and how they fail.

I have found different NAT routers respond differently.  For instance,
using a standard Linksys NAT router and a Netgear FVS 318 router (has
VPN support) produced different results.  Systems connecting from the
LAN using the public IP address on the Linksys router would have their
packets redirected to the LAN retaining their local IP address as the
source.  The Netgear router would actually translate the source address
to the public IP address.  This had some interesting implications for
SMTP and relaying for LAN based clients that were configured such that
the used the public IP address of the SMTP server.  I attribute this
difference to slightly different interpretations of the specs, the one
device performs the NAT prior to routing the packet back to the LAN
while the other device either recognizes the packet remains on the LAN
or reverses the NATing prior to sending the packet on to the
destination. 

As to why a NAT router would cause a slow down for ssh I don't know. 
With the various linksys and netgear devices I have used I have not seen
a slow down in connectivity when using ssh, and I use ssh extensively
both locally and remotely.


-- 
Scot L. Harris
webid at cfl.rr.com

No wonder Clairol makes so much money selling shampoo.
Lather, Rinse, Repeat is an infinite loop!