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  • 1.  Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-02-2024 16:45
      |   view attached

    Hi!

    I am trying to ping an interface (ge-/0/0/3) on an SRX but keep getting a "destination host unreachable" error. I am plugged into the interface through a laptop that is in the same subnet as the interface. The interface itself is in a security zone that allows ping and ssh (which is what I am ultimately trying to do: ssh into the router). I've poked around all over online but haven't been able to find the solution for this. I'll include the security and firewall configs with the post.

    Thank you! 



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    YOOSUF BATLIWALA
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    Attachment(s)



  • 2.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-02-2024 17:06

    which sub-interface on ge-0/0/3? the zone config shows there are multiple (ge-0/0/3.50 and .200). If you're plugged directly into that port you'll need to tag on your laptop to match the interface configs. "destination host unreachable" is usually a routing error more than the host not complaining.

    If you post the interface config it might help more :)



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    Allyn Crowe
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  • 3.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-02-2024 19:38
    Edited by YOOSUF BATLIWALA 07-03-2024 17:16

    Hey Allyn! I'll include the relevant portion of the interface config below. Also, what do you mean by "tag on your laptop"?

    show interfaces | no-more
    ...
    ge-0/0/3 {
            description "To Switch";
            vlan-tagging;
            unit 50 {
                description PROJECT_N;
                vlan-id 50;
                family inet {
                    address 10.10.1.9/26;
                }
            }
            unit 200 {
                description MGMT;
                vlan-id 200;
                family inet {
                    address 172.16.0.5/24;
                }
            }
        }
    ...

     



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    YOOSUF BATLIWALA
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  • 4.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 09:38

    Looking at that interface config it shows that the interface is using 802.1q tags (that's the vlan-tagging command) to receive traffic from 2 separate VLANS (vlan-id 50 and vlan-id 200). This is colloquially called a trunk port. 

    As the description is "To Switch" I'm guessing this is meant to connect to a switch. On the switch you would need to define a port to tag traffic for both of those vlans and connect it to that SRX port. Then you would define an access port on the vlan you're interested in and then try your ping again.

    If you try to connect your laptop directly to that port, the switch doesn't know which subinterface (or VLAN) the traffic is meant for and will drop it. Think of the port like an apartment building with a common entrance. Without the vlan tag, you've delivered a package to the front door, but now none of the occupants don't know who it belongs to so they throw it in the trash. With the vlan tag they know which apartment it's for and can deliver it properly.



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    Allyn Crowe
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  • 5.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 14:52
    Edited by YOOSUF BATLIWALA 07-03-2024 17:18

    The apartment analogy explained things very well for me, thank you! 

    I connected up to the switch and SSH'd into it from ge-0/0/12 (which is configured for SSH access). ge-0/0/9 (on the switch) is configured for connection to the SRX. I'm having a similar issue (this time the ping just never returns an error; it just stays blank). I'll include the switch config below:

    show configuration | no-more
    ...
    interfaces {
    ...
    ge-0/0/9 {
            description "JUNIPER SRX";
            unit 0 {
                accept-source-mac {
                    mac-address (removed);
                    mac-address (removed);
                }
                family ethernet-switching {
                    interface-mode trunk;
                    vlan {
                        members [ Management SATUNNEL];
                    }
                    storm-control default;
                }
            }
        }
    ...
    }
    ...
    vlans {
    ...
    SATUNNEL {
            vlan-id 200;
            forwarding-options {
                dhcp-security {
                    arp-inspection;
                }
            }
        }
    Management {
            vlan-id 50;
            l3-interface irb.0;
            forwarding-options {
                dhcp-security {
                    arp-inspection;
                }
            }
        }
    ...
    }



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    YOOSUF BATLIWALA
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  • 6.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 15:06

    So, looking at that switchport config, it does match the SRX config for VLANs. I'm guessing the config for port ge-0/0/12 is an access port in the management VLAN. So you should be able to ping 10.10.1.9 from your host and whatever the IP on irb.0 on the switch is (I'm assuming it's in the same 10.10.1.9/26 network). It might help if you post the ping command you're running to confirm. 

    If that's still not working then you'll probably need to start looking at security logs to see if/why the traffic is being dropped



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    Allyn Crowe
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  • 7.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 15:32

    Let me show the ge-0/0/12 config just to be sure:

    interfaces {
    ...
    ge-0/0/12 {
            description "RDP Workstation #2";
            enable;
            unit 0 {
                inactive: accept-source-mac {
                    mac-address (removed);
                }
                family ethernet-switching {
                    interface-mode access;
                    vlan {
                        members Management;
                    }
                    storm-control default;
                }
            }
        }
    ...
    }

    and here is the ping command I'm running:

    > ping 10.10.1.9

    additionally, I'm not sure if this is what you're referring to by "IP on irb.0", but here are the details I found in the config:

    show interfaces | no-more
    ...
    Logical interface irb.0 (Index 601) (SNMP ifIndex 504)
        Flags: Up SNMP-Traps 0x0 Encapsulation: ENET2
        Bandwidth: 1Gbps
        Routing Instance: default-switch Bridging Domain: Management
        Input packets : 3561
        Output packets: 6108
        Protocol inet, MTU: 1500
        Max nh cache: 75000, New hold nh limit: 75000, Curr nh cnt: 2, Curr new hold cnt: 0, NH drop cnt: 0
          Flags: Sendbcast-pkt-to-re, Is-Primary
          Addresses, Flags: Is-Default Is-Preferred Is-Primary
            Destination: 10.10.1.0/26, Local: 10.10.1.1, Broadcast: 10.10.1.63
    ...


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    YOOSUF BATLIWALA
    ------------------------------



  • 8.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 15:47

    On SRX: show security packet-drop records | match 10.10.1.9

    Hopefully that will show lines corresponding to your pings along with the reason for the drop. If it doesn't, then your pings are either not being dropped, or never reached the SRX.



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    Nikolay Semov
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  • 9.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet
    Best Answer

    Posted 07-03-2024 15:52

    also I'm assuming the mac addresses listed on port ge-0/0/9 under accept-source-mac are the correct mac addresses? If so everything "looks" good and you should see more under the security logs as Nikolay said. If the packets aren't being dropped by the SRX you may try disabling the mac filtering on the uplink port to the SRX on your switch.



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    Allyn Crowe
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  • 10.  RE: Unable to ping SRX380 from laptop while plugged into it and in the same subnet

    Posted 07-03-2024 20:04

    Originally, I copied the configuration for this switch over from another switch and it looks like I neglected to change the mac addresses to match the new SRX it would be connected to :|

    Deactivating the mac filtering fixed everything right up and I was able to ping the SRX no problem. 

    Thank you so much for your help Allyn and Nikolay!



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    YOOSUF BATLIWALA
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