weblog d’un abbe

20070509

My experiment with inotify and Qt4

Filed under: Experiences, Fun, Hacking, Research — abbe @ 0144

Hello, inotified Qt4 world

My first Qt4 application demonstrating inotify feature of Linux kernel available under GNU GPL from http://wahjava.googlepages.com/ as inotify.tgz. :)

20070319

Setting up an rsync server

Filed under: Experiences — abbe @ 0159

Just 30 minutes back, I’d setup an rsync server. And thanks to Arindam Biswas who gave me the idea of using rsync for upstream transfer. Setting up an rsync server is very easy. Just create an /etc/rsyncd.conf with following content:

uid = nobody
gid = nobody
use chroot = no

[content]
path = /path/to/content
comment = Content

And, now start rsync in server mode with following command:

root@box# rsync --daemon

When done rsyncing kill the daemon process.

20070304

Google Bookmarks via RSS

Filed under: Experiences — abbe @ 2128

Google Bookmarks via RSS
Cool, accessing Google bookmarks via RSS.

20070218

NNTP in GNOME VFS

Filed under: Experiences — abbe @ 2057

NNTP@GNOME-VFS
Well, this is cool. I accidentally clicked on a nntp link in Firefox, and then to my surprise instead of some newsreader application (like Evolution), Nautilus handled it. And then it downloaded recent 104 posts. When I double clicked on a posting, gedit has loaded that news posting. Isn’t it cool worth capturing ;-)

20070210

No LiveJournal for me

Filed under: Experiences — abbe @ 1539

NoLJ4me
No LiveJournal for me. Why ? because I’ve Tor ;-)

20070130

Day of Mistakes

Filed under: Experiences — abbe @ 0241

Yesterday was the day of mistakes. It all started with me submitting updates to my FreeBSD ports maintained by me: x11/libxcb and x11/xcb-proto. I initially submitted both PRs of both ports in misc category. When I realized that I’ve posted in wrong category, then I reposted them into ports category. But at the same time, some FreeBSD committer changed category of my old PRs from misc resulting in duplicate PRs. Then they discarded the duplicate PRs. And then, within an 5-6 hours my port x11/xcb-proto is committed and for x11/libxcb, I received a bug report. Oops, I’d forgotten to include graphics/graphviz as BUILD_DEPENDS, which is causing doxygen to fail during documentation generation.

Finally, XCB v1.0 is in ports :). Thanks to FreeBSD porters for not shouting on me. So from next time, I’ve to be careful not to make any silly mistake.

20070125

0install rocks

Filed under: Experiences — abbe @ 2019

I just tried this great application named 0install, a cool way to deploy apps. No need to su, just a DnD, it will automatically download all dependencies and start the app. If I’m not mistaken, when I was living in properietary software world, there was a similar technology named ClickOnce introduced in .NET Framework 2.0 by Microsoft. Well there is similar technology for Java also, known as Java Web Start.

Anyways, I just installed zeroinstall-injector package from Fedora Extras repository. And then created a launcher for 0install on my xfce4-panel. And now, from this 0installable software directory, I’ve chosen MiniClock to install, just DnDed its Zero install feed on the recently created 0launch launcher. Then it prompted me to trust GPG keys of the software maintainer (for security reasons), and after this it downloaded the dependency and I’m running MiniClock.

Now, to create a shortcut, I’ve to do: 0alias mini-clock http://rox4debian.berlios.de/0install/MiniClock.xml. This will create a shell (/bin/sh) script named mini-clock in ~/bin directory, which will launch the application. Isn’t it cool :)

20061208

Airtel Broadband dropping all outgoing packets to SMTP port

Filed under: Experiences — abbe @ 0011

Well, this I just experienced a few minutes ago, and I think I should blog it. After queuing a mail on 127.0.0.1 smtp server in evening, I found that it was still not delivered. On tailing /var/log/maillog I found that smtp port of smtp.gmail.com is unreachable. I tried to telnet smtp.gmail.com on smtps port, there I got connected. So, I thought Gmail might have dropped support for relaying mails via smtp port, only smtps port. So then I asked one of my friend Edwin, who is fortunately online from non-Indian (or to be more precise, non-Airtel) network, to connect to smtp port of smtp.gmail.com. He told me that he is able to connect. Now, the next thought that came in my mind, Gmail has blocked smtp port of a specific box (though chances of that is very low, as these companies are running cluster of servers for load balancing, and anyways I never worked on clustered network :( ). So I tried another IPv4 address of smtp.gmail.com, still same problem. Then I thought to try connecting to another SMTP server’s smtp, so this time I tried MX of microsoft.com, still same problem, so then I checked my box’s and my ADSL modem’s iptables, but no such rule found. So then I called Gautam to know if he is already experiencing this problem. So he also confirmed me the same. Then Edwin suggested me that I should try tcptraceroute to see where packets were being dropped. Following is the stuff which I did:

[wahjava@chatteau ~]$ sudo tcptraceroute smtp.gmail.com -p 25
Password:
traceroute to smtp.gmail.com (72.14.215.109), 30 hops max, 40 byte packets
 1  172.16.0.1 (172.16.0.1)  1.503 ms  2.419 ms  3.376 ms
 2  rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135)  366.339 ms  367.289 ms  368.254 ms
 3  rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230)  378.217 ms  380.183 ms  384.148 ms
 4  * * *
 5  * * *
 6  * * *
 7  * * *
 8  rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162)  3340.447 ms !X * *
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.gmail.com -p 995
traceroute to smtp.gmail.com (209.85.133.111), 30 hops max, 40 byte packets
 1  172.16.0.1 (172.16.0.1)  1.479 ms  2.408 ms  3.352 ms
 2  rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135)  20.312 ms  22.271 ms  23.240 ms
 3  rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230)  33.203 ms  34.168 ms  36.131 ms
 4  rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162)  48.099 ms  50.066 ms  51.032 ms
 5  203.101.95.181 (203.101.95.181)  52.985 ms  53.949 ms  60.921 ms
 6  203.101.100.29 (203.101.100.29)  84.881 ms  61.776 ms  65.554 ms
 7  203.101.100.237 (203.101.100.237)  99.229 ms  101.843 ms  107.750 ms
 8  202.56.223.29 (202.56.223.29)  103.664 ms  108.346 ms  3062.296 ms
 9  203.208.147.45 (203.208.147.45)  3303.216 ms  303.740 ms  298.521 ms
10  203.208.149.57 (203.208.149.57)  321.219 ms  296.750 ms  297.529 ms
11  * * *
12  209.85.130.6 (209.85.130.6)  337.195 ms  295.753 ms  296.539 ms
13  66.249.95.212 (66.249.95.212)  362.315 ms  352.741 ms  354.526 ms
14  72.14.238.155 (72.14.238.155)  375.188 ms 72.14.239.19 (72.14.239.19)  378.140 ms  386.085 ms
15  216.239.43.13 (216.239.43.13)  379.977 ms 216.239.49.22 (216.239.49.22)  401.926 ms  402.796 ms
16  209.85.133.111 (209.85.133.111)  1969.214 ms  1969.046 ms  1969.025 ms
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.ncr.airtelbroadband.in -p 25
traceroute to smtp.ncr.airtelbroadband.in (202.56.230.30), 30 hops max, 40 byte packets
 1  172.16.0.1 (172.16.0.1)  1.593 ms  2.507 ms  3.457 ms
 2  rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135)  398.424 ms  399.378 ms  403.343 ms
 3  rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230)  404.307 ms  406.274 ms  408.237 ms
 4  rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162)  414.203 ms  416.167 ms  435.135 ms
 5  203.101.95.181 (203.101.95.181)  433.101 ms  434.066 ms  439.032 ms
 6  * * *
 7  smtp.airtelbroadband.in (202.56.230.30)  5374.574 ms  5374.184 ms  5374.113 ms
[wahjava@chatteau ~]$ dig +short smtp.ncr.airtelbroadband.in
202.56.230.27
202.56.230.30
[wahjava@chatteau ~]$ telnet smtp.ncr.airtelbroadband.in smtp
Trying 202.56.230.27...
Connected to smtp.ncr.airtelbroadband.in (202.56.230.27).
Escape character is '^]'.
220 ****************************************************************
^]
telnet> quit
Connection closed.
[wahjava@chatteau ~]$ sudo tcptraceroute smtp.ncr.airtelbroadband.in -p 25
Password:
traceroute to smtp.ncr.airtelbroadband.in (202.56.230.27), 30 hops max, 40 byte packets
 1  172.16.0.1 (172.16.0.1)  1.434 ms  2.346 ms  3.297 ms
 2  rasBTNLDel-static-135.215.56.202.mantraonline.com (202.56.215.135)  263.255 ms  268.210 ms  271.172 ms
 3  rasBTNLDel-static-230.215.56.202.mantraonline.com (202.56.215.230)  270.139 ms  274.102 ms  276.069 ms
 4  rasBTNLDel-static-162.215.56.202.mantraonline.com (202.56.215.162)  280.034 ms  280.991 ms  285.953 ms
 5  203.101.95.181 (203.101.95.181)  287.920 ms  288.886 ms  290.852 ms
 6  203.101.100.198 (203.101.100.198)  291.817 ms  321.753 ms  322.518 ms
 7  smtpout.airtelbroadband.in (202.56.230.27)  973.533 ms  973.181 ms  973.111 ms

As clear from the above dump, that outgoing TCP packets to smtp port are dropped at 202.56.215.162, but 202.56.215.162 allows packets to smtp.ncr.airtelbroadband.in. So, what do you conclude from this ? Anyways, I reported this to their customer care, but customer care representative told me that they’re currently having some problem with some 3rd party websites. And he told me that issue will be resolved tomorrow. Let’s hope it get resolved soon.

20060830

smart package manager

Filed under: Experiences — abbe @ 0215

Being a Fedora Core user, I’ve to use yum for installation, updation of software. yum is a cool package manager but it is quite irritating for me. Why ? Whenever you start yum, it implicitly checks for updates in repositories everytime you run it. That’s quite irritating if you’re on a low speed connection. I’ve used Ubuntu for some time, and used apt there. apt was my favorite package management tool, as you need to explicitly update repositories, but it is not supported very well on Fedora systems, as it need different style of repository (if I’m not mistaken).

And now few weeks back, when I was browsing Fedora Extras, I’ve seen this package manager, named smart . smart is a really smart package management system. It can connect to different kind of repositories. Currently, I’ve tried only rpm-md repositories (aka yum repositories aka RPM meta-data repositories). So, no more yumming only smarting. Its configuration is quite easy. If you’re lazy (or dumb) when it comes to editing configuration files, you can also configure it on command line ;-) . It is able to download simultaneous 2-3 files. And there is not much difference in installing packages via smart, apt-get, or yum.To install package, do :

smart install package

To remove package, do:

smart remove package

To upgrade package, do:

smart upgrade package

To reinstall a package, do:

smart reinstall package

It is currently in beta testing, but I never experienced any problems with it. Happy smarting.

20060722

Day with a more secure modem or a buggy modem or some advanced bridging

Filed under: Experiences — abbe @ 2141

Today, I’ve visited Dad’s Surajmal Vihar office. They recently got an internet connection from Airtel with a static IPv4 address. So, I’ve to just check that internet connection for their Linux server. It was installed on a box with a proprietary OS. I figured out that it is installed in bridge mode, as the computer has a non-private IPv4 address manually set. The Airtel Broadband has provided them with a Zyxel Prestige 600 series modem.

I just plugged out the internet cable (actually a CAT5 cable with a RJ45 connector at both ends) from the box with proprietary OS and inserted in the eth1 of the Linux server, and configured eth1 with the static IPv4 address and appropriate gateway , but to my surprise I’m unable to ping the gateway :-(. Then I rechecked settings, and found them correct, and re-initialized eth1. But still I’m unable to ping the gateway. I re-inserted cable into previous box ( with proprietary OS), and there I’m able to ping the gateway. Well I suspected that modem gets bound to a MAC address, as Gautam thrice told me that in his university, they can’t connect any other network equipment into their university’s network, as MAC addresses of all network devices have to be registered, as each port in the network switch is specifically bound to that MAC address. Anyways, I’m unable to figure out how to change settings in my modem, i.e. I don’t know what is my modem’s IPv4 address. So I just called the Airtel guy, who has installed the connection. He told me that modem is accessible at 192.168.1.1, and he is also surprised why modem is not responding when plugged into a Linux box. So, I replugged my internet cable into my Linux box. And modified eth1 to be in 192.168.1.0/24 network. Then I pinged my modem. :-). And then I telnetted to the modem. And I found the modem interface quite complex as I’m a n00b in networking. So I simply exited from the modem interface without making any changes. And I restored eth1 to the static IPv4 address and appropriate gateway. To my surprise it now worked :)

After some more disconnecting and reconnecting, I finally figured out that this modem gets binded to a MAC address and hence routes packet only for that source MAC address. And to change that binding, one has to just telnet (or probably just ping) the modem (i.e. 192.168.1.1 IPv4 address ) and modem will then record the new MAC address.

This is what I observed today. I don’t know if they did this for the security purpose, or it is just a bug. Chances are more that it is due to security purpose. Or is that some special bridging technique ? I’m confused :-S

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