What I want to solve

I have a configuration file that I do not want to change, because it is shared between many people and is managed by someone else. It has entries similar to this:

serviceAlpha: localhost:8081

serviceBravo: localhost:8082

serviceCharlie: localhost:8083

...

I would like to have the local ports each mapped to a remote host and port, without needing to login (tunnel) via SSH.

For instance:

localhost:8081 -> serviceAlpha:8080

localhost:8082 -> serviceBravo:8080

localhost:8083 -> serviceCharlie:8080

...

What I have tried

I read that /etc/hosts is unable to solve this problem.

I have tried using pf (see here):

echo "

rdr pass inet proto tcp from any to any port 8081 -> serviceAlpha port 8080

" | sudo pfctl -ef -

When I run pfctl -s nat, I get:

No ALTQ support in kernel

ALTQ related functions disabled

rdr pass inet proto tcp from any to any port = 8081 -> ww.xx.yy.zz port 8080

When I run curl -X GET http://localhost:8081/, I get Failed to connect to localhost port 8081: Operation timed out. The same occurs when I replace localhost with 127.0.0.1.

When I run curl -X GET http://ww.xx.yy.zz:8080/, I get the expected response.

I have also tried various socat commands, including:

socat tcp-listen:8081 tcp:ww.xx.yy.zz:8080

curl -X GET http://127.0.0.1:8081/health

> curl: (7) Failed to connect to 127.0.0.1 port 8081: Operation timed out



socat tcp:127.0.0.1:8081 tcp:ww.xx.yy.zz:8080

curl -X GET http://127.0.0.1:8081/health

> curl: (7) Failed to connect to 127.0.0.1 port 8081: Operation timed out

> socat: 2019/02/14 16:27:02 socat[31221] E connect(5, LEN=16 AF=2 127.0.0.1:8081, 16): Operation timed out

One way to accomplish this is using Apache and mod_proxy. You can check a full tutorial on how to setup mod_proxy here (although it is for Linux, the steps for setting up should be similar). Especially check the section Configure Apache For Proxy.

So I think you can setup virtual host for each service and setup apache to listen to 8081, 8082, 8083.

Each virtual host configuration would look something like this:

Listen 8081

<VirtualHost *:8081>

    ProxyPreserveHost On



    <Proxy *>

        Order allow,deny

        Allow from all

    </Proxy>

    ProxyPass / http://ww.xx.yy.zz:8080/

    ProxyPassReverse / http://ww.xx.yy.zz:8080/

</VirtualHost>

The command you want is iptables. The commands are listed below:

echo "1" > /proc/sys/net/ipv4/ip_forward

iptables -t nat -A PREROUTING -i lo -p tcp --dport 8081 -j REDIRECT --to-destination 2.2.2.2:8080

iptables -t nat -A POSTROUTING -j MASQUERADE

I do not believe you are allowed to put a host name into the destination location, but you can try. These changes are not persistent; you need to drop them into a script that is run on startup for persistence.