SolarScale Blog

Network Map

As you can see this is my network at home all contained within one computer using vmware. The load on uranus (the vmware host) is a constant 20% with all these other vm's on. I created the map with xfig.

Random Hackepedia

A broadcast is likened to radio and is by definition one sender and multiple receivers. Ethernet can broadcast, IP can broadcast. Broadcasting is stateless, meaning you cannot use TCP with it. Most broadcasts are done with datagrams.

To read more about Broadcasting go here.

Bug fix

I've made a bugreport for OpenBSD's tcpdump.

At a later time I found out that another similar bug was in the print-icmp6.c code and did a fix for that as well:

--- print-icmp6.c-orig  Fri May 22 13:09:27 2009
+++ print-icmp6.c       Fri May 22 13:10:10 2009
@@ -125,6 +125,7 @@
                        TCHECK(oip->ip6_nxt);
                        hlen = sizeof(struct ip6_hdr);
                        ouh = (struct udphdr *)(((u_char *)oip) + hlen);
+                       TCHECK(ouh->uh_dport);
                        dport = ntohs(ouh->uh_dport);
                        switch (oip->ip6_nxt) {
                        case IPPROTO_TCP:

ICMP Timestamp

Today someone mentioned ICMP timestamps and how they should be firewalled. So I did a bit of research on this. I had the sourcecode handy on BSD and the timestamp returned is seconds since midnight and milliseconds from the microtime clock. The code for this looks somethign like this:

n_time
iptime(void)
{
        struct timeval atv;
        u_long t;

        microtime(&atv);
        t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
        return (htonl(t));
}

# ./cb  -s 172.16.0.3 -d 172.16.0.13 -I 13.0 -F timestamp -vv 
--> interface_gateway: looking up gateway mac for 172.16.0.13
--> interface_gateway: resolved to mac address 0.c.29.4b.46.1e
1 packet written at 60 bytes totalling 60 bytes

I was sorta surprised that NetBSD and FreeBSD had no sysctl to turn this off and especially FreeBSD with it's millions of sysctl's didn't have a knob that turned ICMP timestamps off. I guess the best formula that may make someone feel better about this is just to firewall it locally. I'm tired now, good night.

PS: Oh yes I tested Linux (OpenSuse 10.3) as well and it also replies ICMP timestamps.

Lots of installer movies

Here are some installs that I have done in vmware and made a movie of it. I personally like the installers best in the order openbsd, netbsd, freebsd. I like OpenBSD because you can go back easily which I show in the fourth movie with install tricks.

• FreeBSD 7.2-RELEASE install
• NetBSD 5.0-REL install
• OpenBSD 4.5-current install

• OpenBSD 4.5 install tricks

Make sure you mirror it if you want to share it around. Also if you run windows remember there is codecs found here.

4.5-current install movie #2

I made another movie with vmware. This time it's an install with the latest OpenBSD snapshot. If you saw the movie below this is the same but it's sped up and you'll have to press pause to follow what I did. I tested 2 things. One was whether adding a user was allowed as digits..as you'll see (it did allow digits the last snapshot before that), and the other was escaping out of the installer and checking whether another host was up.

There was one pleasant surprise in that there was a SHA256 checksum on downloaded packages and it reported it being false (as I used the packages from the previous snap on the local ftp site).

• install45-2.avi

Random Hackepedia

A process covers the entire address space for the size of a pointer (32 bit in 32 bit architectures, 64 bit for 64 bit architectures). Since virtual memory is being used, not all areas of a process have real memory assigned to it, only some parts...

To read more about stack on hackepedia click here.

Astronomy question: Spaceship Sun

I'm looking for this information online but I can't find it. We orbit the sun and each quarter orbit we call seasons such as, spring, summer, autumn and winter. The sun also moves into some direction around the galactic center, and I'm wondering into which season does it currently move? How can this be proven? I live in the northern hemisphere so I go by northern directions.

PS: Some progress. We are heading towards the star Vega in the constellation lyra.

PSS: The direction we are moving is also called the solar apex.

4.5-current install movie

I have made a movie with the newest snapshot of OpenBSD. If you've installed OpenBSD before you'll notice some changes in this installer. I don't always go with the defaults but custom install (the partitions).

• 4.5-current Install

I tried watching the .avi with windows xp and it didn't work, but it works with mplayer available on linux and openbsd.

I read up on this and there is a driver for windows which is found here right near the bottom (2nd last).

OK the windows installer works when installed as administrator on an XP box. I'm sure it will work on Vista as well. If you've never seen the install of OpenBSD before perhaps this is worth watching.

Random Hackepedia

Ports are identifiers of protocols that work on the transport layer (layer 4) of the OSI model. TCP and UDP are transport layer protocols that have ports. In TCP and UDP a port is represented by a 16 bit unsigned integer. Thus, the possible port range is 0 through 65535. Port 0 is illegal and no service resides on it.

Read more about Ports at Hackepedia.