Statement introduced in Junos OS Release 9. Configure a device running the Junos OS behind a firewall to initiate outbound SSH connections to communicate with client management applications on the other side of the firewall.
Starting in Release Syntax: To configure keepalive messages, you must set both the retry and timeout attributes:. When that number is exceeded, the device disconnects from the application, ending the outbound SSH connection. If this server is unavailable, the device tries to connect to the next configured server.
The device keeps trying each server in the configured list until the device can establish a connection. If that server is unavailable, the device then attempts to connect to the next configured server. The remaining statements are explained separately. Search for a statement in CLI Explorer or click a linked statement in the Syntax section for details.
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Example: Controlling Management Access on SRX Series Devices
This value serves to uniquely identify the outbound-ssh configuration stanza. Each outbound-ssh stanza represents a single outbound SSH connection. Thus, the administrator is free to assign the client-id any meaningful unique value.
This attribute is not sent to the client management application. Default: port 22 retry number —Specifies the maximum number of times the device attempts to establish an outbound SSH connection before giving up. Default: 3 attempts timeout seconds —Specifies how long the device waits between attempts to reconnect to the specified IP address to establish an outbound SSH connection before giving up. Default: 15 seconds. Each time the device establishes an outbound SSH connection, it first sends an initiation sequence device-id to the management application.
Syntax: To configure keepalive messages, you must set both the retry and timeout attributes: retry number —specifies how many keepalive messages the device sends without receiving a response from the application. Default: 3 attempts timeout seconds —specifies how long the device waits to receive data before sending a request for acknowledgment from the application.
Values: Two methods are available: in-order—Configures the device to reconnect to the first configured server. If you do not specify a routing instance, your device will establish the outbound SSH connection using the default routing table.By Walter J. Goralski, Cathy Gadecki, Michael Bushong. SSH and Telnet are the two common ways for users to access the router. Both require password authentication, either through an account configured on the router or an account set on a centralized authentication server, such as a RADIUS server.
Even with a password, Telnet sessions are inherently insecure, and SSH can be attacked by brute-force attempts to guess passwords. You restrict SSH and Telnet access by creating a firewall filter, which regulates the traffic on a specific interface, deciding what to allow and what to discard. Creating a filter is a two-part process:. However, to make things easier, Junos OS allows you to apply firewall filters to the loopback lo0 interface.
So to limit SSH and Telnet access to the router, you apply the filter to the lo0 interface. The filter shown in the following process is called limit-ssh-telnetand it has two parts, or terms. The Junos OS evaluates the two terms sequentially. Traffic that matches the first term is processed immediately, and traffic that fails is evaluated by the second term. The first term, limit-ssh-telnetlooks for SSH and Telnet access attempts only from devices on the Packets will match this term only if the IP header includes a destination address from the The second term, called block-all-elseblocks all traffic that does not meet the criteria in Step 1.
You can do this step with a basic reject command. You should track failed attempts to access the router so you can determine whether a concerted attack is underway.JUNOS IP Address-SSH
The block-all-else term counts the number of failed access attempts. The first command in the next example keeps track of these attempts in a counter named bad-accesslogging the packet, and sending information to the syslog process.
Creating a filter is half the process. You apply the filter as an input filter, which means that the Junos OS applies it to all incoming traffic destined to the control plane.
He has worked in the networking field for more than 40 years. Cathy Gadecki is coauthor of the first edition of Junos For Dummies.As of writing this article, Juniper recommended version for Junos OS is Up to now there is no functionality of Junos to change the default port number of SSH protocol.
Brute force attack is a type of password attack that constantly tries random username and password. To block the SSH login attack, create a filter and apply it to loopback interface. At first list the trusted IP addresses that will be allowed to access the device and then create prefix-list under policy-options. Now create firewall filter. We will create filter named sshFilter. If you forget this term then you will find yourself locked. Now apply the firewall filter in loopback lo0 interface in inbound or input direction.
Firewall filters will block attack at the very edge level.
In JunOS the packet is first analyze by filters and sent to other path in packet flow process. There is another way to control login attempts in Juniper devices.
The other way is by limiting the number of failed attempts and some threshold parameters. This configuration is applied to all users login in the device. The configuration is done in [edit system login retry-options] hierarchy. Menu Menu. Install Package Version The following two tabs change content below. Bio Latest Posts. You can hire him on UpWork. Bipin enjoys writing articles and tutorials related to Network technologies. Latest posts by Bipin see all.I found this article, however being new to Juniper devices I can't seem to find where to configure this information.
Could someone please tell me how this is accomplished? Go to Solution. By default simply not defining ssh as a system service on the outside inteface will mean that the traffic will be denied. This would be part of the zone definition. The technique I wrote in the tips section is primarily usefull to restrict by source address on an SRX.
This prevents anyone on the internet from being able to attempt to access the SRX. The SRX has the concept of zone and interface bases host services as Kevin mentions. On switches or packet based routers that don't have the security stanza, then the example I posted is used as it is shown. Thanks, I have removed SSH from the interface. I tried to hit it from the outside and it rejected it but is there another way to verify for sure that it is closed? The only verification that I can think of from the firewall side is the test you have run and confirming that the configuration has removed ssh.
Sign In. Global Communities. Community Resources. Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Showing results for. Search instead for. Did you mean:. Thank you! Message 1 of 5 10, Views. All forum topics Previous Topic Next Topic.
Re: Disable SSH on outside interface. A kudo would be cool if you think I earned it. Message 2 of 5 10, Views.
Accepted by topic author rmiller mycustomit. You would apply the filter then at the interface being protected. Message 3 of 5 10, Views. Thank you Rob. Message 4 of 5 10, Views. If both of these have been verified you should be good.After upgrading our SRX from Config validation was successful, no errors whatsoever. After rebooting the box came up fine with the new OS version. We were able to use the previous root password to login to Jweb.
During troubleshooting we generated another user with super-user privileges, and this user can login via ssh an jweb. Changing the root password was possible, but even with the new root password only jweb login is possible. Go to Solution. Just wanted to add the note that it is widely considered best practice on unix systems to disable direct ssh login by root and elevate privledges when needed on the cli. You can find many discussions on this recommendtion to understand the pros and cons via google.
Block SSH Login Attack in Juniper SRX
I'm sure the change in default behaviour is to follow this recommendation and you should enable this only after reviewing and understanding the issues making a conscious choice in the matter and not just because we have always done so. I agree that this change in default behaviour makes sense. However, if a remote upgrade via root ssh would result in a complete lockout, it would have been great if this important change of behaviour were to be found somewhere in the accompanying release docs or the upgrade instructions.
Since it was listed in the documentation listed above, I assumed the change in behavior was also called out in the release notes. But when I pull them up you are correct. No listing of this in the appropriate section. I'll post a note for the documenation team to review this. Building new stacks, new to Juniper So I just upgraded from oob to 15 then to 17, lost access via ssh but can get in under http.
How is that more secure? Now I have to transmit my password in clear text to clear this up The basic idea here on a nix server is that on first login you create a super user account for administrative access.
This is a major change in default behavior to push teams towards this best practice. But it certainly could be better called out during the first install process and upgrade process. Warnings when the non-root accounts do not exist would be a good idea. SRX Services Gateway. Sign In. Global Communities. Community Resources. Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Showing results for.
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Home Questions Tags Users Unanswered. How to specify username for SSH in Juniper router? Ask Question. Asked 4 years, 2 months ago.
Active 4 years, 2 months ago. Viewed 3k times. Model: ACX Version : So to login to second router i need to use local username and password. When i login to first router using TACACS credentials and then try to login to second router from first routerit prompts password field directly without giving username prompt, hence mismatching TACACS username vs local password in second router.
It is taking username of first routerbut i need to force it to use local username. Active Oldest Votes. RobinG RobinG 1, 9 9 silver badges 12 12 bronze badges.
Great it worked. And do you have any idea why Cisco and juniper provide some different set of options for SSH even though SSH is open standard protocol. The protocol is standard, but implementation can be different of course. Cisco probably wrote their own implementation or took the code from a different source. Sign up or log in Sign up using Google.
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Feedback on Q2 Community Roadmap. Related 2. Hot Network Questions. Question feed.This example shows how to limit the management access to the specific IP addresses on an SRX Series devices to manage the device. No special configuration beyond device initialization is required before configuring this feature. To limit the IP addresses that can manage a device, you can configure a firewall filter. This firewall filters must include a term to deny all traffic except the IP address that you allow to manage the device.
You must apply the firewall filter to the loopback interface lo0 as this ensures that only management traffic traffic to the device is filtered. Configure a prefix-list called manager-ip. In this way, you are ensuring that IP address list specified in the prefix list can manage the device. To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, copy and paste the commands into the CLI at the  hierarchy level, and then enter commit from configuration mode.
The following example requires you to navigate various levels in the configuration hierarchy. The configured list is referenced in the actual filter, where you can change your defined set of addresses. Management traffic that uses any of the listed destination ports is rejected when the traffic comes from an address in the list. This configuration applies to traffic terminating at the device itself.
From configuration mode, confirm your configuration by entering show configuration command. If the output does not display the intended configuration, repeat the configuration instructions in this example to correct it.
If you are done configuring the device, enter commit from configuration mode. Help us improve your experience.
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