Author: rtoodtoo

Worked for more than 10 years as a Network/Support Engineer and also interested in Python, Linux, Security and SD-WAN, currently living in the Netherlands and works as a Network Support Engineer. // JNCIE-SEC #223 / RHCE / PCNSE

SSH client preference

There are various SSH clients for Windows platforms and up until couple of months ago I was thinking that the best SSH client for me was SecureCRT but I discovered another one called Mobaxterm. This product really took my attention, primary reason of which is the richness of the feature set. Fist look at what
Read More »

Slow file transfer and TCP Zero Window Probe

Slow file transfers must be really bothering everyone. I have a ZyXEL NSA325 NAS device which has a gigabit interface but I am getting extremely low throughput. Unfortunately this has been a problem I think since I bought this device. Now I could finally get hold of time to troubleshoot the issue. Here is my
Read More »

OSPF route withdraw

OSPF has slightly different way of removing routes compared to BGP. On this short post, I will present how a link failure is propagated to other routers on OSPF domain. For this test, I have the following topology section in which AREA3 is connected to AREA0 and we simulate a link failure on the Junos
Read More »

BGP Route Refresh in JUNOS

What happens when you change a BGP import routing policy in your neighbor configuration? Changes take effect immediately or we need to issue the soft-inbound command to request the routes? Let’s see by an example. We received the route 10.83.0.0/24 from 10.82.1.9 already as you see below. root@J29> show route protocol bgp terse 10.83.0.0/24 inet.0:
Read More »

BGP open message receives a TCP RST

On this micro post, I would like to show one reason why a BGP open message receives a TCP RST. For this test, I set up a BGP neighborship between two peers: PeerA(10.82.1.9) and PeerB(10.82.1.10) PeerA initiates the connection and look what happens in the packet capture. According to the sequence, TCP seems to have
Read More »

OSPF Loop prevention

On this post, I will show an example of loop prevention on OSPF protocol. There is a nice document at here about the principles of loop prevention. What I will just do is to show this on Junos. In order to show this, I am using the following topology; On this topology, J40 and J32
Read More »