Now after hours of googling I finally got it working for me with help of "corkscrew". My ssh-server is running currently on Port 443 (haven't tried yet, whether it would be possible on 22 as well).

~/.ssh/config

Host <my.ssh.server>
    ProxyCommand corkscrew <my.companies.proxy> <proxy.port> %h %p ~/corkscrew-auth

~/.corkscrew-auth

<proxies.username>:<proxies.password>

No I was able to connect to my server via:

ssh <remote.user>@<my.ssh.server> -p 443

Now after hours of googling I finally got it working for me with help of "corkscrew". My ssh-server is running currently on Port 443 (haven't tried yet, whether it would be possible on 22 as well).

~/.ssh/config

Host <my.ssh.server>
    ProxyCommand corkscrew <my.companies.proxy> <proxy.port> %h %p ~/corkscrew-auth

~/.corkscrew-auth

<proxies.username>:<proxies.password>

Now I was able to connect to my server via:

ssh <remote.user>@<my.ssh.server> -p 443