Category Archives: Network Technologies

Network Technologies

WAN load-balancing routers

Intro I got an offer for $20/month broadband access from Centurylink. It got me to thinking, could I somehow use that as a backup connection to my current cable ISP? How would that work? Could I use a Raspberry Pi … Continue reading

Posted in Consumer Tech, Network Technologies, Raspberry Pi | Leave a comment

Obscure curl error explained – partially

Intro Are you, like me, vexed by this curl error: curl: (51) SSL peer certificate or SSH remote key was not OK ? More details I have many Linux systems from which to test. But I can only produce this … Continue reading

Posted in Network Technologies | Tagged | Leave a comment

SSL Interception: troubleshooting

Intro SSl Interception is a reality at some larger companies. From a security perspective it is vital as it permits you to extend your AV scanning, botnet detection, 0-day, DLP, cloud security, etc to your https traffic which is normally … Continue reading

Posted in Network Technologies, Web Site Technologies | Tagged , , , | Leave a comment

Bluecoat ProxySG and DNS using edns seem incompatible

Intro Imagine your DNS server had this behaviour when queried using dig: $ dig drjohnstechtalk.com @146.201.145.30 ; <<>> DiG 9.9.2-P2 <<>> drjohnstechtalk.com @10.201.145.30 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: FORMERR, id: 48905 ;; flags: … Continue reading

Posted in Admin, DNS, Network Technologies | Tagged , , | Leave a comment

Use Raspberry Pi to explore mDNS

Intro I am confounded by the Bonjour field on my d-Link DCS-931L IP webcam. I should be able to use it to see my desired hostname, but it doesn’t take. Why? The details Having a Raspberry Pi on the same … Continue reading

Posted in Admin, Network Technologies, Raspberry Pi | Tagged , | 2 Comments

Switch home router to DD-WRT: FAIL

Intro I am having problems with my home router, a Cisco E1200, especially with the wireless connections. I thought it might be interesting to try to run it using the open source routing code DD-WRT. Since I am a Linux … Continue reading

Posted in Linux, Network Technologies | Tagged , , | Leave a comment

The IT Detective agency: the case of the incompatible sftp client

Intro I was asked for assistance with this sftp problem: $ sftp <user@host> DH_GEX group out of range: 1536 !< 1024 !< 8192 Couldn’t read packet: Connection reset by peer We actually spoke with the operator of the sftp server … Continue reading

Posted in Network Technologies, Security | Tagged , | Leave a comment

drjohnstechtalk now uses HTTP Strict Transport Security, HSTS

Intro I was reading about a kind of amazingly thorough exploit which could be done using a Raspberry Pi zero. Physical access is required, but the scope of what this guy has figured out and put together is really amazing. … Continue reading

Posted in Admin, Apache, Network Technologies, Security | Tagged | Leave a comment

Roll your own dynamic DNS update service

Intro I know my old Cisco router only has built-in support for two dynamic DNS services, dyndns.org and TZO.com. Nowadays you have to pay for those, if even they work (the web site domain names seem to have changed, but … Continue reading

Posted in CentOS, DNS, Linux, Network Technologies, Raspberry Pi, Security, Web Site Technologies | Tagged , , , | Leave a comment

Who’s using the UK Ministry of Defence’s IP addresses?

Intro When I first came upon a spear phishing email a few months ago which originated from the UK’s Ministry of Defence I thought that was pretty queer. Like, how ironic that an invoice scam is coming from a Defense … Continue reading

Posted in Admin, Network Technologies | Tagged | 3 Comments