OpenVPN packet drops

· errors, linux, networking, software

I recently started to notice following error messages on my openVPN server.

ovpn-server[6306]: vpn.rootspirit.com/85.234.x.y:62068 MULTI: packet dropped due to output saturation (multi_process_incoming_tun)
This basically means that the TUN or TAP interface is making more packets than the real (TCP) interface can handle.

As I need to run OpenVPN using the TCP protocol (instead of the faster UDP protocol; as UDP is often blocked in networks I use my VPN in) I experimented by increasing the tcp-queue-limit. The default is 64, and I’ve set it to 256. So far, everything still seems to be working fine (but more packets will be queued before being dropped by OpenVPN, requiring less retransmissions).

Barcamp WiFi: the statistics - #BCA2010

· misc, networking

  • A total of 87 IPs have been handed out (so 87 different MAC addresses)
  • A total of 70 users used the (transparent) Squid proxy, so a few never logged in
  • There was a total of 1.3Gb of HTTP traffic (Saturday only)
  • There was a total of 720.91Mb upload and 2.11Gb download traffic (including Friday evening)
  • Total server uptime was 1 day, 1 hour and 31 minutes :)

Linux gateway/router + unable to access certain (HTTPS) sites

· errors, linux, networking

I’ve had an issue for a while, being unable to access certain websites such as https://fon.com, but also certain parts of the Apple, Fortis and Microsoft site, while other (https) websites worked fine.

Running Wireshark I found that only about 5ish packets got transferred, and all other data to that website abruptly stopped.

I’m using ADSL (EDPnet), which has an MTU of 1492, however, I was able to access all websites from the router (using lynx, for example), but not from any other PC within the network.

Brussels-Midi + iRail

· errors, irail

Apparently the NMBS/SNCB website now makes a difference between “Brussels-Midi” and “Brussels-Midi Eurostar”; same station, different track.

Due to this change, iRail was no longer able to provide any scheduling information which included Brussels-Midi.

I’ve made a quick and dirty work around (by including “+ Eurostar” in the drop down menu), solving this bug.

However, please, NMBS/SNCB, please please please provide an API or report such changes to web developers.

As it is now, if you manually fill in Brussels-Midi and do not add the Eurostar text, the iRail website will not be able to to look up the requested information.

Public DNS server

· networking

I have been running a public DNS server for private purpose (never liked my ISP’s DNS servers, and the root servers were usually located too far away (at least those with easy to remember IPs).

Anyway, been testing it since this summer, and so far it’s been working great.

the DNS server running on a Debian virtual machine, hosted by Rootspirit, near Amsterdam.

IP address: 85.12.6.171

Hostname: vm1.rootspirit.com

Might not be an easy to remember IP address (unlike 4.2.2.1), but as I use that IP pretty much every day, it’s okay for me. ;)