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Posts in Networking
Viewing wireless networks with wigle
I heard about the wigle and restyredwagon websites sites a while back, and finally had a chance to look through their content tonight. If you haven't heard of these nifty sites, they both contain geographic maps of 802.11 wireless networks. Since the rustyredwagon website overlays wigle data on google maps, you can click a location and get a wealth of information (e.g., SSID, Mac Address, Vendors, and a keyword indicating if WEP/WPA is utilized) on the 802.11 networks in a region. You can also view satellite photos, which adds a whole new twist to scouting out 802.11 networks ( can we call this war surfing?)…
$ read more →Determining the reason behind rx_overflow values (part 1).
While performing some routine checks on one of the servers I support, I noticed numerous input errors on Gigabit Ethernet interface zero: Since this was a Sun server running Solaris 9, I fired up the kstat(1m) utility to find the cause of these errors: After reviewing the kstat(1m) output I noticed that the rx_overflow value was well in excess of 150k. Since the word "overflow" is never a good sign, I started to research this issue by reading the manual page for gld(7D). This page contains descriptions for the generic LAN driver (gld) kstat values, but for some reason didn't include a description for rx_overflow (the name is self-evident, but I wanted a definite answer). After a quick Google search I came across the following information in the the Sun Maximizing Performance of a Gigabit Ethernet NIC Interface blueprint: "When rx_overflow is incrementing, packet processing is not keeping up with the packet arrival rate…
$ read more →Debugging Solaris in.rarpd issues
While performing a routine jumpstart this week, one of my friends was receiving a steady stream of Timeouts while attempting to jumpstart a system: He had used the jumpstart server earlier in the week to build a system, and was uncertain why the server he was jumpstarting couldn't get an IP address. He asked me if I could take a look at the problem, so I fired up snoop on the jumpstart server to see if the RARP requests were reaching the server: The requests were indeed getting to the server, but for some reason the server wasn't sending anything back to the client. I double checked all the configuration files (e.g., /etc/bootparams, /etc/ethers, /etc/hosts), and then double checked that the host had valid entry in /etc/tftpboot. Everything appeared to be correct, so I fired up truss to watch what in.rarp was doing: The truss output indicated that certain RARP requests were being processed by in.rarpd, but the MAC address of the system my friend was attempting to jumpstart was not showing up…
$ read more →Converting from nslookup to dig
I have used nslookup for years to access information in the Domain Name Systems (DNS), and was sad to see that it was moved to the "deprecated" state when dig (domain information groper) was released. Since I knew nslookup(1m) inside and out, I put off learning about dig, and instead focused on learning other interesting technologies. I recently wanted to add TSIG support to a DNS server, and needed to be able to test signing keys. I didn't see support in nslookup, so I decided to sit down and learn everything there was to know about dig…
$ read more →Comparing SOA records with dig
Whiel reading through the dig documentation today I came across the "nssearch" option: This nifty little option can be used to view the SOA record maintained by all servers authoritative for a domain. If you choose to avoid using AXFR and manually update zone files, this option could be extremely useful.
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