Tag Archives: networking

Workaround for Neighbour Discovery failure, for static-configured IPv6 on Linux: Use IPv4 gateway mac for IPv6

Here’s a shell script to figure out what the IP4 gateway MAC address is, and to set that as the IP6 gateway MAC: This was necessary for a machine where the gateway decided that responding to neighbour solicit requests was … Continue reading

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Ignoring out-of-band network policy systems with iptables

I’ve been working on parental controls using an out-of-band policy engine. It is easy to subvert, if you care to, since the controls it implements are very light, and it is not actually part of the conversation between you and … Continue reading

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What are the IP addresses for NS records of co.za?

In short? 99.8% of the time, they are these: ns1.coza.net.za. IN A 66.135.62.20 ns.coza.net.za. IN A 206.223.136.200 ns4.iafrica.com. IN A 196.7.142.131 ns0.is.co.za. IN A 196.4.160.17 ns0.neotel.co.za. IN A 41.160.0.4 coza1.dnsnode.net. IN A 194.146.106.74 And the remaining 0.2% of the time?  … Continue reading

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Invasion of the evil androids

Google says you are too stupid to rule your own life.  They say this by their Android phone operating system, in which they do not give you, the owner and operator of the device, root permissions.  This means: You cannot … Continue reading

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The sound of outage

Here’s a song to sing the next time your network goes down.  Click the play button on the youtube karaoke, and sing it yourself: Hello outage my old friend I’ve come to talk with you again Because of vulnerability creeping … Continue reading

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VMWare + ipfix + NAT = intermittent fail

So I put all of these things together a while ago for bandwidth reporting: VMWare‘s netflow reporting – I configured a virtual distributed switch to send netflow reporting to a collector.  Every time some machine runs up its internet usage, the … Continue reading

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Netgear STP bug (or something)

I found a fun bug today. We have a stack of netgear switches in our office – and we keep getting disconnected at odd times. I already found a switch which did not have STP enabled, and turned that on, … Continue reading

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Not your regular bot driven UDP flood

After weeks of battling Joomla/JCE sites that insist on running evil code and spewing denial of service traffic, we had a machine today sending UDP floods. This, it turns out, is not a hacked machine sending spews of botnet traffic … Continue reading

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Compiling Netgear Firmware

Having ranted about Netgear’s terrible support for their old stuff, I have finally managed after many moons to recompile the software they provide, so that I can brick my router.  The trick is to do the compiling as root on … Continue reading

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Can’t send mail because of iptables -A FORWARD -p tcp –tcp-flags SYN,RST SYN -j TCPMSS –clamp-mss- to-pmtu

So, you have a Netgear DGN1000 N150 router or possibly any other Netgear router, and you have it set up with: DSL – VPI=8, VCI=35, LLC, PPPOE Wireless Ethernet One day, as you are sending mail, you notice that mail … Continue reading

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