proxytunnel on MAC

Use Proxytunnel on M1 Mac

When trying to connect from my M1 mac to the lab’s servers, I failed multiple times and had to use my old windows laptop to connect from WSL.

Our server requires a proxy jump for security reasons, so we use the following lines in the ssh_config file

Host hostname
    ProxyCommand proxytunnel -E -p hostname:port -d %h:%p

To install proxytunnel on Mac, upon google “proxytunnel mac”, the top 2 links will take us to Homebrew Formulae, which is a popular package manage on Mac. To install proxytunnel, the webpages suggest

brew install proxytunnel

With successful installation with brew, when I try to ssh, the following error message appears

> ssh me@hostname
Via hostname:port -> hostname:22
Certificate verification failed (unable to get local issuer certificate)
kex_exchange_identification: Connection closed by remote host
Connection closed by UNKNOWN port 65535

I tried to solve this problem, but there is no discussion nor solution on the internet. I blamed this on the M1 chip, but I was wrong.

How to fix

It turns out, although brew said the install is successful, the dependence of proxytunnel is not complete. My current solution is to uninstall it from brew and reinstall with MacPorts.

If you have MacPorts installed, then

brew uninstall proxytunnel
sudo port install proxytunnel

then ssh should be working with the same commands.