How to keep netcat open using it as a TCP tunnel?

Question

Say I am doing something like this: (bsd variant of nc)

nc -k -l 8080 <fifo | nc 10.90.34.18 80 >fifo

This works great, I can use the server this is run on as a proxy to reach 10.90.34.18.

However, after performing a curl, it looks like the second nc command exits.

How can I prevent this?

"This works great" Does it? How? What happens when the server on 10.90.34.18:80 closes the connection? — user313992, Jul 15, 2019 at 6:11
Shell is bash. When the server closes the connection I believe this is what causes the second netcat process to exit. I suppose it would be more correct to say "This works great for a single connection". — cat pants, Jul 15, 2019 at 9:02

cat pants · Accepted Answer · 2019-07-15 22:58:07Z

1

The answer is to use a while loop like so:

while true
do
  nc 10.90.34.18 80 >fifo
done < <(nc -k -l 8080 <fifo)

answered Jul 15, 2019 at 22:58

cat pants

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