topic Block all SSH outbound in General Topics

Block all SSH outbound

Ivy_Vo — Fri, 31 Jul 2020 19:45:37 GMT

For a home user who uses VPN to access internal network, how can we block all his SSH outbound connection to internet?

Re: Block all SSH outbound

Remo — Fri, 31 Jul 2020 19:57:38 GMT

Hi @Ivy_Vo

Are these computers managed by your company or are these devices owned by the users?

Re: Block all SSH outbound

Ivy_Vo — Fri, 31 Jul 2020 19:59:54 GMT

They use the company laptops, but how does that matter? Thanks!

Re: Block all SSH outbound

Remo — Fri, 31 Jul 2020 20:20:27 GMT

Ok, I actually does not matter who owns the laptop. It matters if these laptops are centrally managed for example with active directory. As you are asking this question I assume you have split tunneling configured and only traffic towards your internal network is sent through the vpn tunnel. In this case you would need to block the outgoing ssh connections towards the internet locally on these laptops.

If you route everyrhing (0.0.0.0/0) into the tunnel, then simply create a rule on the firewall, but I thought this would be too easy for a question here 😉

Re: Block all SSH outbound

BPry — Fri, 31 Jul 2020 20:22:36 GMT

@Ivy_Vo,

Are you tunneling all of the traffic through GlobalProtect or are you using split-tunnel. The question @Remo mentioned is important because I'm assuming that you are using split-tunnel based off of your question.

If you are tunneling all the traffic through GlobalProtect, you would simply build out a security rulebase entry that denies all ssh traffic from your GlobalProtect zone to your untrust zone. I'm guessing you're asking the question because this isn't the case.

Re: Block all SSH outbound

Ivy_Vo — Fri, 31 Jul 2020 20:58:21 GMT

@Remo and @BPry

Thank you all for explanation! I'm very new to Palo Alto.

Yes that is the case. We are using GlobalProtect to tunneling all the traffics and having a policy to deny all ssh application from GP zones to Untrust Zone. The policy was created a week ago but we got 0 hit counts. I think there are other ways to do this or I might miss something...

Re: Block all SSH outbound

BPry — Fri, 31 Jul 2020 21:00:11 GMT

@Ivy_Vo,

Possibly a simple policy precedence issue. Is your policy to deny the traffic above the policy currently allowing said traffic or not?

Re: Block all SSH outbound

Ivy_Vo — Fri, 31 Jul 2020 21:20:21 GMT

Yes, it is above.

Re: Block all SSH outbound

Remo — Fri, 31 Jul 2020 21:42:46 GMT

The block rule is a userbased rule, is the connection maybe from a user not specified in this deny-rule?

Re: Block all SSH outbound

BPry — Fri, 31 Jul 2020 21:51:31 GMT

@Ivy_Vo,

Might be a good idea to include one of the allow log entires you are still seeing for said user.