river.fysh.org runs a Squid proxy providing service only for localhost on port 3128. This is configured as the system-wide web proxy for lake itself, but can also be used remotely if you utilise a tunnel.
Using with (Open)SSH on a 'Unix' machine
If you need to use it from a 'Unix' machine with SSH available then do something like:
ssh -L localhost:8080:localhost:3128 river.fysh.org
Then set your local web browser to use localhost:8080 as its proxy. Note the above command will also log you into lake, just leave it sat there whilst you need the proxy.
Using with PuTTY on a Windows machine
Keeping it alive
If you encounter problems with this session timing out then try:
while :; do echo -n 0 ; sleep 60 ; done
which should keep the connection alive by echoing a '0' character every minute.