[j-nsp] protect ssh and telnet

Fri Apr 15 12:10:37 EDT 2016

Thanks Krasi, Hmmm, this looks very interesting, I want to try it in my lab… also, please let me know if this will ONLY work for my routing-instance vrf “one” interfaces… 

My vrf “one” is where my public/vulnerable ip’s live…

I don’t need to protect my default core vrf which is all 10.x.x.x and that domain is behing a mgmt. net firewall boundary

Aaron

From: Krasimir Avramski [mailto:krasi at smartcom.bg] 
Sent: Friday, April 15, 2016 6:51 AM
To: Aaron <aaron1 at gvtc.com>
Cc: Chris Jones <ipv6freely at gmail.com>; Juniper-Nsp <juniper-nsp at puck.nether.net>
Subject: Re: [j-nsp] protect ssh and telnet

Hi Aaron,

Below is commit script which is building dynamic prefix list (containing local IPv4 addresses) you could reference in FTF:

krasi# show system scripts commit

allow-transients;

file ifl-addr-v4.slax;

krasi# run file show /var/db/scripts/commit/ifl-addr-v4.slax

version 1.0;

ns junos = "http://xml.juniper.net/junos/*/junos";

ns xnm = "http://xml.juniper.net/xnm/1.1/xnm";

ns jcs = "http://xml.juniper.net/junos/commit-scripts/1.0";

import "../import/junos.xsl";

match configuration {

    <transient-change> {

        <policy-options> {

            <prefix-list replace="replace"> {

                <name> "ifl-addr-v4";

                  for-each (interfaces/interface/unit/family/inet/address) {

                            var $address = substring-before(name, "/");

                            <prefix-list-item> {

                              <name> $address;

                           }

                  }

             }

         }

     }

}

krasi# show policy-options |display inheritance |display commit-scripts

prefix-list ifl-addr-v4 {

    1.1.1.1/32 <http://1.1.1.1/32> ;

    10.10.111.1/32 <http://10.10.111.1/32> ;

}

krasi# set interfaces xe-0/0/0 unit 0 family inet address 2.2.2.2/30 <http://2.2.2.2/30> 

[edit]

root# commit

commit complete

[edit]

root# show policy-options |display inheritance |display commit-scripts

prefix-list ifl-addr-v4 {

    1.1.1.1/32 <http://1.1.1.1/32> ;

    2.2.2.2/32 <http://2.2.2.2/32> ;

    10.10.111.1/32 <http://10.10.111.1/32> ;

 }

Best Regards,

Krasi

On 13 April 2016 at 23:43, Aaron <aaron1 at gvtc.com <mailto:aaron1 at gvtc.com> > wrote:

Thanks Chris, but apparently the Juniper ACX5048 is an exception to the lo0 rule…  see link

http://kb.juniper.net/InfoCenter/index?page=content <http://kb.juniper.net/InfoCenter/index?page=content <http://kb.juniper.net/InfoCenter/index?page=content&id=KB28893&actp=search&viewlocale=en_US&searchid=1305252358192> &id=KB28893&actp=search&viewlocale=en_US&searchid=1305252358192> &id=KB28893&actp=search&viewlocale=en_US&searchid=1305252358192

I’ve been able to accomplish protecting telnet/ssh on my ACX5048 like this…

set routing-instances one forwarding-options family inet filter input protect-5048

set firewall family inet filter protect-5048 term 1 from destination-address 1.1.1.1/32 <http://1.1.1.1/32> 

set firewall family inet filter protect-5048 term 1 from protocol tcp

set firewall family inet filter protect-5048 term 1 from destination-port telnet

set firewall family inet filter protect-5048 term 1 from destination-port ssh

set firewall family inet filter protect-5048 term 1 then count protect-5048-counter

set firewall family inet filter protect-5048 term 1 then discard

set firewall family inet filter protect-5048 term 2 then accept

1.1.1.0/24 <http://1.1.1.0/24>  is a subnet on an interface in vrf “one” on my acx5048…

The only thing is that I will need to make it a policy with my colleagues that if/when we churn public address space or add new interfaces on our acx5048’s, part of the process will be to add a line to our firewall acl…

set firewall family inet filter protect-5048 term 1 from destination-address 1.1.2.1/32 <http://1.1.2.1/32> 

set firewall family inet filter protect-5048 term 1 from destination-address 1.1.3.1/32 <http://1.1.3.1/32> 

etc

QUESTION – does anyone know how to make this firewall acl or include a confition or policy somehow to apply the firewall policy to ONLY LOCAL ROUTES (/32’s) ?  that would be nice , so that I would never have to add/subtract specific ip addresses in this firewall policy.

Aaron

From: Chris Jones [mailto:ipv6freely at gmail.com <mailto:ipv6freely at gmail.com> ]
Sent: Wednesday, April 13, 2016 10:05 AM
To: Aaron <aaron1 at gvtc.com <mailto:aaron1 at gvtc.com> >
Cc: juniper-nsp at puck.nether.net <mailto:juniper-nsp at puck.nether.net> 
Subject: Re: [j-nsp] protect ssh and telnet

To answer OPs actual question:

What you're looking for is an RE filter, applied to lo0. A great resource explaining them and some best practices, etc. check out Doug Hank's Day One book: http://www.juniper.net/us/en/training/jnbooks/day-one/fundamentals-series/securing-routing-engine/

On Tue, Mar 29, 2016 at 10:26 PM, Aaron <aaron1 at gvtc.com <mailto:aaron1 at gvtc.com>  <mailto:aaron1 at gvtc.com <mailto:aaron1 at gvtc.com> > > wrote:

I'm new to Juniper. and I'm looking to protect ssh/telnet on all interfaces
on my juniper ACX5048's.

In Cisco you can protect the virtual interface (vty) with a acl
(access-class) so that any remote login attempts (ssh or telnet) or
protected.

How do I protect ssh and telnet globally in Junos ?  I only want to allow
ssh and telnet from certain trusted management subnets.

Aaron

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--

Chris Jones
JNCIE-ENT #272
CCIE# 25655 (R&S)

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