sclient

Secure Client for exposing TLS (aka SSL) secured services as plain-text connections locally.

Also ideal for multiplexing a single port with multiple protocols using SNI.

Unwrap a TLS connection:

sclient whatever.com:443 localhost:3000

> [listening] whatever.com:443 <= localhost:3000

Connect via Telnet

telnet localhost 3000

Connect via netcat (nc)

nc localhost 3000

cURL

curl http://localhost:3000 -H 'Host: whatever.com'

A poor man's (or Windows user's) makeshift replacement for openssl s_client, stunnel, or socat.

Table of Contents

• Install
• Usage
• Examples
• Build from Source

Install

Mac, Linux

curl -sS https://webinstall.dev/sclient | bash

curl.exe -A MS https://webinstall.dev/sclient | powershell

Downloads

Check the Github Releases for

• macOS (x64) Apple Silicon coming soon
• Linux (x64, i386, arm64, arm6, arm7)
• Windows 10 (x64, i386)

Usage

sclient [flags] <remote> <local>

• flags

  • -s, --silent less verbose logging
  • -k, --insecure ignore invalid TLS (SSL/HTTPS) certificates
  • --servername <domain> spoof SNI (to disable use IP as <remote> and do not use this option)
  • --alpn <protocol-list>

• remote

  • must have servername (i.e. example.com)
  • port is optional (default is 443)

• local

  • address is optional (default is localhost)
  • must have port (i.e. 3000)

  -alpn string acceptable protocols, ex: 'h2,http/1.1' 'http/1.1' (default) 'ssh' (default "http/1.1") -insecure ignore bad TLS/SSL/HTTPS certificates -k alias for --insecure -s alias of --silent -servername string specify a servername different from (to disable SNI use an IP as and do use this option) -silent less verbose output

Examples

Bridge between telebit.cloud and local port 3000.

sclient telebit.cloud 3000

Same as above, but more explicit

sclient telebit.cloud:443 localhost:3000

Ignore a bad TLS/SSL/HTTPS certificate and connect anyway.

sclient -k badtls.telebit.cloud:443 localhost:3000

Reading from stdin

sclient telebit.cloud:443 -

sclient telebit.cloud:443 - </path/to/file

Piping

printf "GET / HTTP/1.1\r\nHost: telebit.cloud\r\n\r\n" | sclient telebit.cloud:443

Testing for security vulnerabilities on the remote:

sclient --servername "Robert'); DROP TABLE Students;" -k example.com localhost:3000

sclient --servername "../../../.hidden/private.txt" -k example.com localhost:3000

API

See Go Docs.

Build from source

You'll need to install Go. See webinstall.dev/golang for install instructions.

curl -sS https://webinstall.dev/golang | bash

Then you can install and run as per usual.

git clone https://git.rootprojects.org/root/sclient.go.git

pushd sclient.go
  go build -o dist/sclient cmd/sclient/main.go
  sudo rsync -av dist/sclient /usr/local/bin/sclient
popd

sclient example.com:443 localhost:3000

Install or Run with Go

go get git.rootprojects.org/root/sclient.go/cmd/sclient
go run git.rootprojects.org/root/sclient.go/cmd/sclient example.com:443 localhost:3000