21,018 reputation
12247
bio website ripple.com
location Oakland, CA
age 44
visits member for 2 years, 11 months
seen 2 days ago

I am Chief Cryptographer at Ripple Labs and one of the architects of the Ripple payment system.


Jun
18
comment Network latency caused by incorrect cable?
I don't believe this answer is correct. The vast majority of crossover cables don't work with gigabit Ethernet. I suspect this is because most crossover cables predate gigabit Ethernet and so don't comply with the gigabit crossover standard (which requires all pairs be swapped).
Jun
18
comment Port Forwarding on Cisco Router
That's very strange, because connection refused means that something is refusing the connection.
Jun
18
comment freebsd reducing network bandwidth after some uptime
Falls from what? And how exactly are you measuring network throughput?
Jun
18
comment What does “1-gig switch port” mean in co-location terms?
The "500 GB total monthly transfer" suggests that there is no 95th percentile billing policy but that instead the limit is on the total data sent/received per month.
Jun
18
comment What does “1-gig switch port” mean in co-location terms?
@eric2872 Don't use terms like "gb" because they're extremely ambiguous. That could mean 1 billion bits per second, it could mean 2^30 bytes per second, or anything in between.
Jun
18
comment Port Forwarding on Cisco Router
Where did you test from? Did you test from outside your network? Did you confirm that there's a listening socket bound to 192.168.1.20:80 for traffic to be NATted to?
Jun
18
comment Port Forwarding on Cisco Router
You don't really describe the problem very well. What exactly happens? How did you test whether the rule was working and what results did you get? (You may have just tested incorrectly -- for example, by testing from inside your own network when your rule only applies to traffic from the outside.)
Jun
4
comment Mysql crashing, oom-killer, out of memory, tuning issues?
Swapping will not slow things down, that's a myth. There are two kinds of swapping -- required and opportunistic. Required swapping is an alternative to crashing which, as this question shows, slows things down a lot more. Opportunistic swapping (what you're suggesting he reduce by turning swapiness down) is done specifically because it speeds thing up by making more physical memory available for cache. I gave you a +1 though because you are probably right about the key issue -- he needs more swap.
Jun
2
comment Restrict whole system on certain cores except a few process?
You're probably going about this the wrong way. The solution is probably just to give the latency-sensitive threads absolute priority rather than waste cores when there's no latency-sensitive work to be done. Tell us more about what the latency sensitive threads do.
Jun
2
comment if I name an image with a %2F, I cannot access it and when navigating to it, I get a 404
Your question is really vague. When you say "name an image with a %2F", what does that mean? The filename contains a %2F? Or some tool that lets you name images is given such a name? And what is the "it" that doesn't let you access it? Does it give an error when accessing it from the website? What does the URL look like? What does the URL normally look like? You seem to be assuming we know what you normally do so you only have to tell us about the case that doesn't work. But we have no idea how things normally work for you.
May
26
comment Linux cached memory: Over 85% of cached memory and using swap
The idea that swap makes a system slow is entirely false. Your system will use swap only when it is beneficial to do so.
May
25
comment Why drop caches in Linux?
@AaronHall For RAM to provide any benefit, it must be used. It's the RAM your system is using that is improving its performance.
May
22
comment Iperf UDP listening on used port
It's really not clear what you're asking. Are you asking how more specific binds work to allow two applications to bind to the same UDP port? Or are you asking how to troubleshoot a problem with Asterisk? If you want help with a problem, you need to describe the problem to us. All you've done is state one symptom.
May
22
comment In a HP server, can low voltage DIMMS and standard voltage DIMMs be mixed?
It is acceptable if there is some voltage at which both DIMMs are specified to work and you can configure the motherboard to provide that voltage.
May
21
comment Switch and ARPxMAC
@kasperd Now that I think about, there's no reason. The source MAC must always be unicast.
May
20
comment How can I find my peak bandwidth usage over a period of time?
@TecBrat Those statistics won't help you. Knowing how much bandwidth you used won't tell you how much you needed. (For example, your backups might spike to a very high value just because there's lots of bandwidth between the backup machine and this machine. But the backup performance might be perfectly adequate with 1/10th the bandwidth.) You need to figure out what you need, not what you're using.
May
20
comment Why drop caches in Linux?
@ivcode Then you should find and fix the problem with that server rather than trying to avoid the conditions that cause it. If my car stalled every time I made a sharp right turn, avoiding sharp right turns is a lousy fix.
May
14
comment configure single /32 ip address to FreeBSD server
Are you bridging to the VM or routing to it?
May
14
comment configure single /32 ip address to FreeBSD server
Did they assign you a /32 that is already routed on an Ethernet network with some other netmask? Or are they just routing a /32 to you and the machine already has an IP address? In what sense is that IP address associated with a particular physical Ethernet interface? You need to understand how this is supposed to work to configure it correctly. There are multiple possibilities. (A /32 primary makes no sense for Ethernet. What other machine could you ever talk to? No other IP would be on that network.)
May
13
comment The permission to run 'ls' is denied
You're probably going to have to boot from rescue media and fix enough permission to make the system manageable.