Tag Archives: linux

Getting around Comcast port 25 block

Comcast started blocking outbound port 25 on my cable modem yesterday. I can understand why — it stops a lot of infected machines from spamming the world. But it also broke the ability of my security webcam from sending me pictures to my server whenever it detects movement, and the cam firmware has no option to use the alternate authenticated port 587.

So this blog entry talks about how I got around the port 25 block so my webcam can continue to email images.

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Personal VOIP/PBX using Asterisk, part 2

This is part two of my series on how to set up an asterisk server for home use on a Linode VPS — but is applicable to any host that doesn’t have additional hardware telephony devices installed in the server. Please refer to Part 1 for how to set up the dummy timing module.

Also, before continuing, please read my little sidebar post about IP telephony codecs. Most specifically the part on adding iLBC codec to the asterisk config. Then “read more” below for the rest of this post.

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Personal VOIP/PBX using Asterisk, part 1

Background

Voice over IP is simply placing phone calls over the Internet instead of  traditional phone lines. This means the calls are usually cheaper, but not free in many cases since often the telco lines have to get involved at some point to either originate or terminate a call. However, true voip calls are almost always free, no matter where in the world they are.

There are many commercial products out there already that makes this easy for a user, like Vonage and Comcast’s voice, but they have fairly hefty monthly fees. They do usually offer unlimited domestic (U.S.) calls.   But they also have drawbacks, like, ah not working if the power or cable goes out.

The next few posts will document my experience in rolling my own voip service.

Part 1 is compiling the support drivers on my “Linode” for Asterisk.

Click through for the details…

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Rescaning SCSI bus for SAN disk adds

This should not have been as difficult to do as it was. Simple concept, add disks and hence LUNs to the scan, and you want to use them on your host without having to umount all disks and reload the scsi driver.

There’s a script to rescan the scsi bus from a website that automates the process, but it didn’t work on one host I tried it.

I found that since we use qlogic drivers there’s a command that has to be run first to let the driver know that a rescan is coming (I guess).


echo "scsi-qlascan" > /proc/scsi/driver-name/adapter-id

After running it, I got this goodness in fdisk for the new device! 🙂

Disk /dev/sdd: 2000.4 GB, 2000414572544 bytes

Moving data with mirrors

The main data volume on the system at work ran out of PEs due to the old default PE size of 4 MB and 64k of PEs being in the volume group. There’s no way to change that without recreating the volume group, and blowing away everything. So I have to move the 250 gigs of crap to somewhere else, then delete the old volume group, recreate it, then move everything back. Since moving that much data requires several hours and hence downtime to users, that’s not good.

So, the idea is to move the data around live. This requires making a RAID 1 mirror on top of lvm — not usually done this way. It also requires learning enough about mdadm to be able to create a mirror without destroying the good data (ouch). The process of intially creating the mirror will require the regular lvm device be unmounted and the RAID (md) device mounted. But after that is done, the syncing of the mirror can happen live. Hence downtime is kept to an absolute minimum.

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