> For the complete documentation index, see [llms.txt](https://kchuene.gitbook.io/data-communication-project/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kchuene.gitbook.io/data-communication-project/archive/ssh.md).

# SSH

Configurations for detection and response against potentially malicious traffic.

## Re-Routing

Consider the policy as that only connections from the controller node are allowed to the Production SSH service. With this we want to reroute all non-controller traffic (internal and external) to the **Cowrie SSH** honeypot. 

**Enable IP Forwarding**

Enable machine to forward/redirect traffic to other hosts in the network

{% code overflow="wrap" lineNumbers="true" %}

```
sysctl net.ipv4.ip_forward
sudo sysctl net.ipv4.ip_forward=1
```

{% endcode %}

**Redirect Non-Local Connection Attempts**

{% code overflow="wrap" lineNumbers="true" %}

```
sudo iptables -t nat -A PREROUTING -p tcp --dport 22 ! -s 192.168.56.0/24 -j DNAT --to-destination 192.168.56.101:22
```

{% endcode %}

where

* `-t nat` When a packet that creates a new connection is encountered.
* `-A PREROUTING` Alter packet as soon as it comes in.
* `-j DNAT` Alter the destination address of the packet to --to-destination.

also, the `! -s 192.168.56.1/24` option checks for packets not coming from the local network.

Lastly we solve the **Missing Return Path** issue where the **Cowrie** server attempts to send the response directly to the source IP, but the source IP rejects it because it was expecting it from the Production node (the one the source IP attempted to connect to in the first place)

{% code overflow="wrap" lineNumbers="true" %}

```
sudo iptables -t nat -A POSTROUTING -p tcp --dport 22 -d 192.168.56.101 -j MASQUERADE
```

{% endcode %}

where

* `-A POSTROUTING` Alter packet as it is about to go out
* `-j MASQUERADE` specify our IP as the return address.

{% embed url="<https://hackertarget.com/cowrie-honeypot-ubuntu/>" %}

{% embed url="<https://linux.die.net/man/8/iptables>" %}

{% embed url="<https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands>" %}


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