slaptijack

In TCP window scaling and broken routers posted in July of 2004, LWN.net's corbet points out that certain routers are setting the RFC 1323 window scale to 0. This effectively sets the TCP window size for the transmission to the minimum value and greatly inhibits performance. As corbet notes …

To enable RFC 1323 Window Scaling and increase the TCP window size to 1 MB on FreeBSD, add the following lines to /etc/sysctl.conf and reboot.

net.inet.tcp.rfc1323=1  
kern.ipc.maxsockbuf=16777216  
net.inet.tcp.sendspace=1048576  
net.inet.tcp.recvspace=1048576

You can make these …

The original TCP specification included a window size no larger than 64 KB. This limitation was introduced by the 16 bit header that specified window size. To achieve the recommended 1 MB window size, RFC 1323 TCP extensions must be enabled. The rest of this post is a somewhat detailed …

Trying to debug an <acronym title="Asterisk Gateway Interface">AGI</acronym> in Asterisk can be a frustrating experience. The main problem is that STDERR only outputs to the terminal Asterisk was started from. In most cases, this means the terminal is the server console. If your Asterisk server is sitting …

Note: Although this is a continuation of the TCP Performance Tuning article series, it's also valuable as a standalone reference.

This is a list of 14 congestion control algorithms available in TCP. I'm presenting it in alphabetical order.

1. BIC TCP - Binary Increase Congestion Control, this is the default congestion control …

Note: Stanislav Shalunov wrote an excellent article on TCP over WAN Performance Tuning and Troubleshooting. In this series of articles, I want to summarize his findings and provide tuning suggestions for popular operating systems.

Most operating systems today ship with TCP stacks optimized for either LAN (high speed, low latency …

Note: Now that Google is hosting email domains for free, it has become an interesting alternative for both new and old domains. As always, I've changed the names to protect those affected.

Transitioning a domain to Google can be an arduous task. Once you have set up the domain with …

XHTML Character Entity Reference

Digital Media Minute's Jim Rutherford has developed an invaluable reference in his XHTML Character Entity Reference. With this reference in hand, I can finally ditch all my little notes about copyrights, trademarks, and cedillas. Here's an explanation of how the page works in Jim's own …

Deciding whether to use <acronym title="Remote Authentication Dial-In User Service">RADIUS</acronym> or <acronym title="Terminal Access Controller Access Control System Plus">TACACS+</acronym> for <acronym title="Authentication, Authorization, Accounting">AAA</acronym> functionality on a Cisco-based network seems straight-forward. After all, if the network uses Cisco, shouldn't the AAA …

Important commands: sips

A few folks have asked me where I got the nice looking Software Update icon for my post regarding Apple's Security Update 2007-004. First, let me say, "Thanks for noticing!" Second, let me point out that Steve Jobs will probably be knocking on the door of the …