Category Archives: Networking

Find out what’s really happening in your network with LogRhythm NetMon Freemium

I recently discovered that LogRhythm, as well as very a full-featured Security Intelligence Platform and SIEM, also provide a “freemium” Network Monitor. The “freemium” refers to that fact that the software is 100% free, full-featured and not time-limited, but is capacity-limited. … Continue reading

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Connection State Announcer

I’ve been having some very annoying problems with my home broadband where the connection keeps dropping every few minutes. I wrote this quick script to monitor a site on the internet and tell me when it can’t be reached anymore, … Continue reading

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Testing for open ports with PowerShell

Want to find out if a TCP port is open via a firewall and/or if something is listening on that port? From within a script? You can use PowerShell. A colleague found this, which uses System.Net.Sockets.TcpClient from the .NET framework … Continue reading

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Active Directory Dynamic DNS broken by Juniper SRX firewall ALG

Last week a Juniper SRX firewall was put in to replace an older internal firewall. This week a load of Windows Servers dropped out of Active Directory DNS. The scavenging period in AD DNS was configured to be 7 days. Coincidence? I … Continue reading

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Network Optimisation for Office 365 and other external or cloud services

These are some notes from a short video I just watched. Scanning through these notes will take less time than watching the whole 13 minute video. Plus I’ve added links and more info Latency PsPing is one of the SysInternals … Continue reading

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PowerShell: Find MTU

I had some issues caused by MTU recently, and decided to write a script to test for the Maximum Transmission Unit that a network or host could cope with. I originally started off by using the PowerShell Test-Connection cmdlet, but … Continue reading

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Posted in Networking, PowerShell, Scripting | Tagged , , , , , , , , | 2 Comments

SBS 2008: Emails not received or bouncing

Small Business Server 2008 contains (amongst other things) Exchange 2007. This means that email handling is done on-premises rather than by an SMTP/IMAP/POP3/Exchange server hosted out on the internet somewhere. This has good points and bad points. The good is … Continue reading

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Posted in Exchange, Networking, Windows | Tagged , , , , , , , , , , , , , , , | 2 Comments

Microsoft Remote Connectivity Analyser

Handy online utilities to check for issues. Can also help decypher SMTP headers. https://testconnectivity.microsoft.com/

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Janet CSIRT Denial Of Service Briefing

Quick summary of some of the stuff from the short presentation this morning, 15th Feb 2013, by Bradley Freeman and James Davis from Janet CSIRT. There tend to be three main types of denial of service attack, and they don’t … Continue reading

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VMware ESX/ESXi issues with Broadcom 5719 quad port Gb NIC

I’ve got some new servers with Broadcom quad port 1Gb Ethernet NICs in, model 5719. Nine of the servers are running ESX 4.1 update 2 502767, one is running ESXi 5.0 update 1 623860. Two servers have experienced this issue. … Continue reading

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Posted in Networking, vSphere | Tagged , , , , , , , , , , , | 40 Comments