For some time now, I’ve been running OpenWRT on an RT-N66U device. I initially set that because I had previously been using my Debian-based file/VM server as a firewall, and this had some downsides: every time I wanted to reboot that, Internet for the whole house was down; shorewall took a fair bit of care and feeding; etc.
I’ve been having indications that all is not well with OpenWRT or the N66U in the last few days, and some long-term annoyances prompted me to search out a different solution. I figured I could buy an embedded x86 device, slap Debian on it, and be set.
As expected, with hardware like that to work with, it was a lot more capable than OpenWRT and had more features. However, I encountered a number of surprising issues.
The biggest annoyance was that the system wouldn’t allow me to set up a static DHCP entry with the same IP for multiple MAC addresses. This is a very simple configuration in the underlying DHCP server, and OpenWRT permitted it without issue. It is quite useful so my laptop has the same IP whether connected by wifi or Ethernet, and I have used it for years with no issue. Googling it a bit turned up some rather arrogant pfsense people saying that this is “broken” and poor design, and that your wired and wireless networks should be on different VLANs anyhow. They also said “just give it the same hostname for the different IPs” — but it rejects this too. Sigh. I discovered, however, that downloading the pfsense backup XML file, editing the IP within, and re-uploading it gets me what I want with no ill effects!
So then I went to set up DNS. I tried to enable the “DNS Forwarder”, but it wouldn’t let me do that while the “DNS Resolver” was still active. Digging in just a bit, it appears that the DNS Forwarder and DNS Resolver both provide forwarding and resolution features; they just have different underlying implementations. This is not clear at all in the interface.
Next stop: traffic shaping. Since I use VOIP for work, this is vitally important for me. I dove in, and found a list of XML filenames for wizards: one for “Dedicated Links” and another for “Multiple Lan/Wan”. Hmmm. Some Googling again turned up that everyone suggests using the “Multiple Lan/Wan” wizard. Fine. I set it up, and notice that when I start an upload, my download performance absolutely tanks. Some investigation shows that outbound ACKs aren’t being handled properly. The wizard had created a qACK queue, but neglected to create a packet match rule for it, so ACKs were not being dealt with appropriately. Fixed that with a rule of my own design, and now downloads are working better again. I also needed to boost the bandwidth allocated to qACK (setting it to 25% seemed to do the trick).
Then there was the firewall rules. The “interface” section is first-match-wins, whereas the “floating” section is last-match-wins. This is rather non-obvious.
Getting past all the interface glitches, however, the system looks powerful, solid, and well-engineered under the hood, and fairly easy to manage.