~/blog

  • Configuring NAT66 on ScreenOS

    I recently had to deploy redeploy an old NetScreen 5GT to segregate a production LAN and create a small lab network. The production LAN has a routable IPv6 /64 prefix, delivered via a Hurricane Electric IPv6 tunnel. The lab network also required IPv6 connectivity. We also recently obtained a /48 prefix from Hurricane Electric, so…

  • The Mystery of the Disappearing Polycom Idle Logo

    I occasionally have to support customers running very old Polycom SoundPoint IP firmware releases. One of these customers has their company logo installed on their phones as an idle display bitmap (eg. centrally provisioned phone wallpaper). After a recent firmware upgrade at this customer, the logo disappeared, and it took several hours and a fair…

  • When coding with Lua, remember to think like a lunatic…

    I recently experienced some strange behaviour from a Lua script I wrote to dynamically generate an XML string for a FreeSWITCH directory user, which used the string.format() function to populate a format string with values returned from an ODBC database connection. Being used to Python (and many other scripting languages), I assumed that an empty…

  • Exporting a X.509 certificate public key from Junos

    I’ve just spent the last couple of hours trying to find a way to export the public key from a locally generated, self-signed X.509 certificate on a Juniper SRX-100 firewall. Apparently there is no Junos CLI command to do this, so after poking around the filesystem from a shell on the box, I found the…

  • Cisco QoS Exam

    My CCNP was due to expire in August, so I needed to pass any 642-* exam to renew it. I decided to sit the Cisco QoS exam (642-642), since it was one of two remaining exams I need to become CCIP. After a few weeks of study on and off, I’m pleased to say I…

  • Cisco Wireless LAN Controllers and DHCP Option 43

    I recently had to install a Cisco Wireless LAN Controller (2112, if you’re interested), and had the usual fun and games with getting it to properly understand DHCP Option 43. For the uninitiated, option 43 is a vendor specific option, which, in the case of Cisco WLCs, is/are the manager IP address(es) of controllers that…

  • The Amazing Unmanaged Trunk Mode Switch

    Have you ever needed to set up a bunch of equipment on a boardroom table or some other temporary location, and needed both native and 802.1q tagged VLANs, but only had one available switchport? A quick n’ dirty solution is to use an unmanaged switch, such as one of the numerous 8-port desktop switches from…

  • Retrieving NetScreen/SSG config via scp

    There are a couple of prerequisites before you can copy the config from a NetScreen or SSG via scp. First, obviously ssh and scp need to be enabled: set ssh version v2 set ssh enable set scp enable And of course, you need to enable ssh management on the interface you’re going to connect to…

  • Retrieving IOS running-config via scp

    Ok, now I’ve only tested this with routers running IOS – it may be a little different with Catalyst switches, since they store their config on flash, rather than nvram. On the other hand, it may be exactly the same, since we’re retrieving running-config, not startup-config. First, you need to ensure that ssh and scp…

  • Back in Germany

    I’m finally back in Berlin, after several unplanned delays. I’ll be here until at least April 2008, seeing how things pan out. I’m considering doing a TESOL or CELTA course, to open up the possibility of teaching English (either here, Russia, or Japan). Having had such a great time in Japan has made it difficult…