22,438 reputation
12451
bio website ripplelabs.com
location Oakland, California
age 45
visits member for 3 years, 7 months
seen 5 hours ago

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


Feb
25
comment Is it possible to find a computer's physical location in a room?
It depends on the precise details of the hardware you're working with and what kind of access you have. For example, if they have USB ports and you can deploy software to them, you can deploy a program that causes a system to alert you (say, by email) when a new USB device connects to it. Then just attach a USB flash drive to each machine in turn, keeping track of the connection order.
Feb
21
comment passenger-memory-stats doesn't show Private memory consumption
Likely your operating system doesn't track what memory usage is private.
Feb
16
comment Remove SSL warning with internal websites, with Chrom
@MikeMestnik The client has to additionally verify that the certificate is appropriate for the URL specified. Just knowing that the cert was issued by the CA is insufficient, as an attacker can easily get a cert (and matching key) signed by a trustworthy CA. This question is dealing with those appropriateness checks, not certificate validity checks.
Feb
13
comment Is there any reason to keep the power option on default “Balanced” instead of “high performance”?
You are incorrect that the only negative effect is the electricity bill. There are several other negative effects that come from the additional heat produced and temperatures of the components, including an increased risk of performance loss due to thermal throttling. (And the CPU may not be the only component that thermally throttles.)
Jan
26
comment Apache accepting requests to other servers?
Welcome to the Internet. Everyone who operates a server on the Internet has to have a strategy for dealing with the "baseline noise" that pretty much all Internet servers see.
Jan
21
comment Apache 2.4 prefork, MySQL 5.6 and 2GB RAM
Your top output shows 1.4GB of RAM (68%) inactive, which means it's available for use for any purpose. Why do you think there's a problem?
Jan
13
comment kworker consuming +90% IO and zero disk write
You may want to use perf to find out what kworker is doing as a troubleshooting step.
Jan
13
comment Where is my RAM going?
Use slabtop to see if it's the dentry cache.
Jan
7
comment Linux is sending ARP requests to hosts in other subnets?
Something is probably wrong in the netmasks or routing table on host A.
Jan
6
comment svchost.exe -k regsvc using over 1.2 GB RAM
How did you determine that it was using over 1.2 GB of RAM? (Please be as specific as possible. What tool did you use? What exactly did it report?)
Jan
5
comment Where did my RAM go?
@Benjamin I don't know any way to see what's in the dentry cache. But running strace may be instructive. Do you use libcurl? What's your app doing?
Jan
5
comment Where did my RAM go?
@Benjamin Follow my link for one example of how this can happen. Also, look at what the web application is actually doing.
Jan
2
comment Clearing Memory (RAM) Cache on CentOS
Are you seriously asking how to get your computer to waste more memory rather than using it efficiently?
Jan
2
comment How many bits of entropy per byte read from /dev/random and /dev/urandom?
@DanielKauffman I have no idea what that means.
Jan
2
comment How many bits of entropy per byte read from /dev/random and /dev/urandom?
@DanielKauffman You can already read however many bytes you want/need from /dev/urandom directly. Hashing is really only helpful if you want to combine entropy from multiple sources.
Dec
30
comment Data Transfer Speed Hardware Config
@Alan When it maxed out, what maxed out? CPU? Memory? I/O?
Dec
30
comment multiple internet connection at office
@Krunal Support for enterpricey features like tunnels.
Dec
24
comment Iptables block connection from specific IP - to another IP
@Beginner Something is very wrong with your understanding of something because the comment above is incoherent. What does it mean for a host name to use an IP address as a DNS server? And what traffic are you trying to block? Traffic to a DNS server?
Dec
16
comment HP Procurve 2920 VLANs with DHCP cannot ping
That doesn't make sense. If the server already has an IP address inside 192.168.x.0, it shouldn't need a route. And if it doesn't have an IP address inside 192.168.x.0, it shouldn't know how to reach 192.168.x.2 without a route that would also work for the rest of 192.168.x.0/24.
Dec
11
comment Swap 99% but regular memory fine
What is swappiness set to?