After upgrading the Laptop OS when I try to login to my old machine I got this error message....

jay@jay:~$ ssh -p 2222 jay@jpudasaini.com.np
Unable to negotiate with 192.168.156.101 port 2222: no matching host key type found. Their offer: ssh-dss

I can't access the system, here is the solution

jay@jay:~$ ssh -oHostKeyAlgorithms=+ssh-dss -p 2222 jay@jpudasaini.com.npThe authenticity of host '[jpudasaini.com.np]:2222 ([192.168.156.101]:2222)' can't be established.
DSA key fingerprint is SHA256:J#$/zFpzr05gdfrshufHHOQvss6NQcEpPMgKlibTc.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '[jpudasaini.com.np]:2222,[192.168.156.101]:2222' (DSA) to the list of known hosts.
Password:

A Network Administrator command  which help diagnosis DNS related issue. However to understand this,  you should better to know how DNS works.

How to troubleshoot DNS related issue.

1. NSLOOKUP example display "A Record" (IP Adress) of the domain




C:\Users\jpudasaini>nslookup jpudasaini.com.np 8.8.8.8
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Non-authoritative answer:
Name:    jpudasaini.com.np
Address:  216.239.32.21

A Non-Authoritative Answer is a response from Cache. A DNS server is
authoritative for zones actually holds it.

The above output shows "A Records" (IP Adress) of the domain
"jpudasaini.com.np". Which is actually query to the public Google DNS. If
you don't put DNS after the domain, it will used your default DNS, in my
case I have used public DNS.

2. MX Record using -query=mx

MX (Mail Exchange) record maps for the specific domain name to verify mail
exchaing servers on that domain.


C:\Users\jpudasaini>nslookup -query=mx gmail.com 8.8.8.8
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Non-authoritative answer:
gmail.com       MX preference = 40, mail exchanger =alt4.gmail-smtp-in.l.google
.com
gmail.com       MX preference = 20, mail exchanger =alt2.gmail-smtp-in.l.google
.com
gmail.com       MX preference = 10, mail exchanger =alt1.gmail-smtp-in.l.google
.com
gmail.com       MX preference = 30, mail exchanger =alt3.gmail-smtp-in.l.google
.com
gmail.com       MX preference = 5, mail exchanger =gmail-smtp-in.l.google.com

From the above example we can say that  4 MX records used for gmail
domain, the number associat with mx reference the preference of mail
server. Lower the number, higher the preference. So
gmail-smtp-in.l.google.com is the first server which received the mail at
first.

3. NS Record using -query=ns

NS (Name Server) records maps a domain to a list of DNS servers
authoritative for that domain. Here is example of name server which are
associated with jpudasaini.com.np doamain.

C:\Users\jpudasaini>nslookup -query=ns jpudasaini.com.np 8.8.8.8
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Non-authoritative answer:
jpudasaini.com.np       nameserver = ns4.afraid.org
jpudasaini.com.np       nameserver = ns2.afraid.org
jpudasaini.com.np       nameserver = ns1.afraid.org

4. SOA Record using -query=soa

 C:\Users\jpudasaini>nslookup -query=soa jpudasaini.com.np 8.8.8.8
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Non-authoritative answer:
jpudasaini.com.np
        primary name server = ns1.afraid.org
        responsible mail addr = dnsadmin.afraid.org
        serial  = 1511030001
        refresh = 86400 (1 day)
        retry   = 7200 (2 hours)
        expire  = 2419200 (28 days)
        default TTL = 3600 (1 hour)

SOA record (start of authority) which provides the authoritative
information, as well as e-mail address, serial no of the respective
domain.


5. Reserve DNS lookup

The reverse DNS look-up using IP Adress as argument to nslookup
C:\Users\jpudasaini>nslookup 216.239.32.21 8.8.8.8
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Name:    any-in-2015.1e100.net
Address:  216.239.32.21


6. Using Specific DNS Server

Make query using particular name server instead of using default DNS server.


C:\Users\jpudasaini>nslookup jpudasaini.com.np ns1.afraid.org
Server:  UnKnown
Address:  50.23.197.95

Name:    jpudasaini.com.np
Address:  216.239.32.21

EoMPLS is point to point L2 VPN services which is used to transport all Ethernet frame received on particular Ethernet or VLAN,  its also called Any Transport over MPLS(ATOM) means this technology can connect like Frame-Relay, PPP, Ethernet,ATM etc.

IOS used
c7200-adventerprisek9-mz.151-4.M

Logical Topology

It's been a long time I'm away from blogging due to some R&D on the network with Juniper boxes. On this tutorial I'm going to configure very basic MPLS VPN configuration in GNS3. After that we go for EoMPLS configuration.

This is the logical topology for this tutorial.

We already configure our QEMU in GNS3 and run our vSRX Router. Now its time to configure DHCP server in our vSRX router. Lets began.
Logical Diagram for this tutorial



To configure DHCP server

Assign Lowest and highest IP range
root# set system services dhcp pool 192.168.1.0/24 address-range low 192.168.1.50 high 192.168.1.200

Assign DNS server (in my case I had used Router interface IP)
root# set system services dhcp pool 192.168.1.0/24 name-server 192.168.1.1

Assign IP address of the router
root# set system services dhcp pool 192.168.1.0/24 router 192.168.1.1

Assign the lease time
root# set system services dhcp pool 192.168.1.0/24 default-lease-time 3600



Assign DHCP as an allowed inbound service for the interface which we are going to enable DHCP.

root# set security zones security-zone untrust interfaces ge-0/0/1 host-inbound-traffic system-services dhcp

Assign IP address to the client faced interface.
root# set interfaces ge-0/0/1 unit 0 family inet address 192.168.1.1/24



Check our client get the IP Address from the server.

In this tutorial I'm going to run vSRX JunOS in QEMU and configure it as DHCP Server. Lets began with installing vSRX into QEMU.

I have try vSRX to run into Vbox but never succeeded. So I better to choose QEMU otherwise waste of time.

In my case I had used junos-vsrx-12.1X46-D10.2-domestic to mount into QEMU. Search for it.
Now we have to convert our .vdi file into .image, for that use following command

cd d:\junos\
c:\Program Files\GNS3\qemu\>qemu-img.exe convert -O qcow2 d:\junos\junos-vsrx-12.1X46-D10.2-domestic-disk1.vdi d:\junos\junos-vsrx-12.1X46-D10.2-domestic.img

We just made our image ready to run into QEMU. Go the GNS3

Note: Strongly recommended to use QEMU in linux and enable KVM otherwise it eats up all your CPU and RAM.

-nographic -smp 2 -enable-kvm

>edit>preference>choose "QEMU VMs"
Click on "New" Choose "Default " Gave Name "vSRX" (in my case).

While doing some lab test, this weird syslogd message appear every seconds on the console terminal, so it was very difficult to complete the lab.