Tool for port forward & intranet proxy, just like lcx/ew, but better

Why write?
lcx and ew are awesome, but can be improved.
when I first used them, I can't remember these complicated parameters for a long time, such as tran, slave, rcsocks, sssocks.... The work mode is clear, why do they design parameters like this(especially ew's -l -d -e -f -g -h)
Besides, I think the net programming logic could be optimized.
For example, while running lcx -listen 8888 9999 command, client must connect to :8888 first, then :9999, in iox, there's no limit to the order in two ports. And while running lcx -slave 1.1.1.1 8888 1.1.1.1 9999 command, lcx will connect two hosts serially, but it's more efficient to connect in concurrent, as iox does.
What's more, iox provides traffic encryption feature. Actually, you can use iox as a simple ShadowSocks.
And iox also provides UDP traffic forward.
Of course, because iox is written in Go, the static-link-program is a little large, raw program is 2.2MB (800KB after UPX compression)

Feature

• traffic encryption (optional)
• humanized CLI option
• logic optimization
• UDP traffic forward

Usage
You can see, all params are uniform. -l/--local means listen on a local port; -r/--remote means connect to remote host

Two mode
fwd：
Listen on 0.0.0.0:8888 and 0.0.0.0:9999, forward traffic between 2 connections

./iox fwd -l 8888 -l 9999


for lcx:
./lcx -listen 8888 9999

Listen on 0.0.0.0:8888, forward traffic to 1.1.1.1:9999

./iox fwd -l 8888 -r 1.1.1.1:9999


for lcx:
./lcx -tran 8888 1.1.1.1 9999

Connect 1.1.1.1:8888 and 1.1.1.1:9999, forward between 2 connection

./iox fwd -r 1.1.1.1:8888 -r 1.1.1.1:9999


for lcx:
./lcx -slave 1.1.1.1 8888 1.1.1.1 9999

proxy
Start Socks5 server on 0.0.0.0:1080

./iox proxy -l 1080


for ew:
./ew -s ssocksd -l 1080

Start Socks5 server on be-controlled host, then forward to internet VPS
VPS forward 0.0.0.0:9999 to 0.0.0.0:1080
You must use in pair, because it contains a simple protocol to control connecting back

./iox proxy -r 1.1.1.1:9999
./iox proxy -l 9999 -l 1080       // notice, the two port are in order


for ew:
./ew -s rcsocks -l 1080 -e 9999
./ew -s rssocks -d 1.1.1.1 -e 9999

Then connect intranet host

# proxychains.conf
# socks5://1.1.1.1:1080

$ proxychains rdesktop 192.168.0.100:3389

Enable encryption
For example, we forward 3389 port in intranet to our VPS

// be-controller host
./iox fwd -r 192.168.0.100:3389 -r *1.1.1.1:8888 -k 656565


// our VPS
./iox fwd -l *8888 -l 33890 -k 656565

It's easy to understand: traffic between be-controlled host and our VPS:8888 will be encrypted, the pre-shared secret key is 'AAA', iox will use it to generate seed key and nonce (Normally, nonce shouldn't be reused. But consider that iox's encryption is only for bypassing IDS, in order not to allocate extra space, the TCP stream encryption will reuse the nonce), then encrypt with Xchacha20 (replace AES-CTR with Xchacha20 in v0.3 version)
So, the * should be used in pairs

./iox fwd -l 1000 -r *127.0.0.1:1001 -k 000102
./iox fwd -l *1001 -r *127.0.0.1:1002 -k 000102
./iox fwd -l *1002 -r *127.0.0.1:1003 -k 000102
./iox proxy -l *1003 -k 000102


$ curl google.com -x socks5://127.0.0.1:1000

Using iox as a simple ShadowSocks

// ssserver
./iox proxy -l *9999 -k 000102


// sslocal
./iox fwd -l 1080 -r *VPS:9999 -k 000102

UDP forward
Only need to add CLI option -u

./iox fwd -l 53 -r *127.0.0.1:8888 -k 000102 -u
./iox fwd -l *8888 -l *9999 -k 000102 -u
./iox fwd -r *127.0.0.1:9999 -r 8.8.8.8:53 -k 000102 -u

NOTICE: When you make a multistage connection, the Remote2Remote-UDP-mode must be started last, which is the No.3 command in above example
UDP forwarding may have behavior that is not as you expected. Actually, on GitHub now, there are only examples of forwarding a local listener to a remote host, so I can only implement them with my understanding
You can find why in the source code. If you have any ideas, PR / issue are welcomed