---
type: concept
title: SSH Tunneling at Universität Greifswald
tags: [ssh, networking, proxyjump, remote-access]
related: [ssh-gateway, vpn-zugang]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_technische_infrastruktur_vpn_ssh_gateway.md"]
---

# SSH Tunneling at Universität Greifswald

SSH Tunneling (specifically using the **ProxyJump** method) is the recommended way to access internal university systems via the [[ssh-gateway]]. This method routes the connection through the gateway directly to the target system, avoiding the limitations of a two-step login.

## Implementation Methods

### Command Line Interface (CLI)
Users can establish a tunnel using the `-J` (Jump) flag:
`ssh -o VerifyHostKeyDNS=yes -J ACCOUNTNAME@ssh-gateway.uni-greifswald.de BENUTZERNAME_IM_ZIELSYSTEM@FQDN-ZIELSYSTEM`

### SSH Configuration File (`~/.ssh/config`)
For persistent access, the URZ recommends configuring the `~/.ssh/config` file:

```ssh
VerifyHostKeyDNS yes

Host ssh-gateway
    HostName ssh-gateway.uni-greifswald.de
    User ACCOUNTNAME

Host ALIASNAME
    HostName FQDN-ZIELSYSTEM
    User BENUTZERNAME_IM_ZIELSYSTEM
    ProxyJump ssh-gateway
```
Once configured, the connection can be initiated simply with `ssh ALIASNAME`.

## Advantages over Direct Login
Using a tunnel is superior to logging into the gateway and then the target system because:
- **Authentication**: It supports Public-Key authentication on the target system.
- **File Transfer**: It allows direct file transfers (e.g., via SCP or SFTP) to the target system without intermediate storage on the gateway.
