In my formative days of learning network hacking, SSH tunnelling was amongst the first tunnelling techniques that I learnt. I still remember trying to repeatedly decode my notes and diagrams on the rather cumbersome syntax of single port forwarding with the -L and -R flags, which at the time was taught as “the way to do it”. If your foothold is (luckily) a Linux server, then you’re blessed with the -D flag to spin up a SOCKS proxy on the foothold itself to access the network via proxychains.