AS Number Stats on Linux

Posted on by Randy

I’ve got a couple of Linux machines that are sitting outside of the Sflow ‘zone’ and AS traffic stats go unmeasured. I wanted to get a rough idea on the number of connections per AS number so here’s a little app that parses netstat and sorts AS numbers by number of connection.

NOTE1: This won’t work on Cpanel servers due to tmp restrictions.

NOTE2: Specify an alternative (e.g newer) GeoIPASNum.dat file with the –geo option.

wget http://djlab.com/stuff/asnum
chmod +x asnum
./asnum

Example output:

[root@mx1 ~]# ./asnum
(18) | RFC1918 or BOGON
(11) | AS29889 Fast Serv Networks, LLC
(4) | AS3320 Deutsche Telekom AG
(2) | AS7922 Comcast Cable Communications, Inc.

Quick and (very) dirty cron script

#!/bin.sh
#/root/doasnum.sh
#*/5 * * * * /root/./doasnum.sh >> /var/log/asnum.log

thedate=`date`
echo "***********************"
echo $thedate
/root/asnum
echo "***********************"

Don’t forget to rotate the logs.

#/etc/logrotate.d/asnum
/var/log/asnum.log
{
        rotate 7
        daily
        missingok
}
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Obfuscate or Encrypt Perl

Posted on by Randy

There are 3 primary options:

1. Use PAR with PAR::Filter::Obfuscate or PAR::Filter::Crypto

2. Use Filter::Crypto::CryptFile (requires certain modules installed on target system)

3. Encrypt modules with Module::Crypt.

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Clone a live linux system with Rsync over SSH

Posted on by Randy

Update: 5/3/17 — Add additional notes for CentOS7 (dracut + grub2) and XenServer targets

All commands are run on new server.

1. Boot into rescue mode (iso, pxe, ect).

2. Create partitions with ‘fdisk /dev/sda’. Type 83 for non-RAID fs, 82 for swap, type fd in the case of RAID (all partitions). Flag boot partition as bootable.

In the case of SSD, add -S 32 -H 32 to the fdisk command and start the first partition on sector 2 for proper alignment.

If using RAID, duplicate the partition table after creating it on the first disk:

dd if=/dev/sda of=/dev/sdb bs=1 count=64 skip=446 seek=446

2. Create RAID array (if applicable).

# For SSD, add: --chunk=128
mdadm --create /dev/md0 -e 0.90 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1  ## /boot
mdadm --create /dev/md1 -e 0.90 --level=1 --raid-devices=2 /dev/sda2 /dev/sdb2  ## Swap
mdadm --create /dev/md2 -e 0.90 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3  ## /

3. Create filesystems

For spin disk:

mkfs.ext4 /dev/md0 # /dev/sda1 for non-RAID
mkfs.ext4 /dev/md2 # /dev/sda3 for non-RAID

For SSD (non RAID):

mkfs.ext4 -b 1024 -E stride=128,stripe-width=128 -O ^has_journal /dev/sda1
mkfs.ext4 -b 1024 -E stride=128,stripe-width=128 -O ^has_journal /dev/sda3

For SSD (RAID):

mkfs.ext4 -b 1024 -E stride=128,stripe-width=256 -O ^has_journal /dev/md0 ## stripe-width = stride x N disks
mkfs.ext4 -b 1024 -E stride=128,stripe-width=256 -O ^has_journal /dev/md2 ## stripe-width = stride x N disks

4. Mount filesystems

mkdir /mount
mount /dev/md2 /mount  ## /dev/sda3 for non-RAID
mkdir {/mount/boot,/mount/dev,/mount/sys,/mount/proc,/mount/tmp}  
mount /dev/md0 /mount/boot ## /dev/sda1 for non-RAID

5. Sync filesystems with Rsync over SSH (Ex: 1.2.3.4 is source machine)

rsync -aHxv --numeric-ids --progress root@1.2.3.4:/* /mount --exclude=/dev --exclude=/proc --exclude=/sys --exclude=/tmp
rsync -aHxv --numeric-ids --progress root@1.2.3.4:/boot/* /mount/boot --exclude=/dev --exclude=/proc --exclude=/sys --exclude=/tmp  ## Only if /boot is on separate partition in source machine

If applicable: stop mysql on the source machine and resync the databases to prevent corruption:

rsync -aHxv root@1.2.3.4:/var/lib/mysql/* /mount/var/lib/mysql

6. Update mdadm.conf

mdadm --examine --scan > /mount/etc/mdadm.conf

7. Update fstab (if needed)

ls -la /dev/disk/by-uuid # to get new UUID's
vi /mount/etc/fstab

8a. Install bootloader (CentOS5, CentOS6 / grub)

grub
root (hd0,0)
setup (hd0)
root (hd1,0)  ## for RAID
setup (hd1)  ## for RAID
exit

8b. Install bootloader (CentOS7 / grub2)

Do step 10 (chroot) first, then this

grub2-install /dev/sda # Use correct device(s), repeat as neccesary
# Good time to clean up /etc/default/grub, then:
grub2-mkconfig -o /etc/grub2.cfg

# If migrating to Xen/XenServer:
dracut --add-drivers "xen-blkfront xen-netfront xen:vbd" --regenerate-all --force

9. Optional: change IP address if both machines need to be online

vi /mount/etc/sysconfig/network-scripts/ifcfg-eth0

10. Hint: you can chroot into the cloned filesystem – for example – initramfs rebuilding:

cd /mount/
mount -t proc proc proc/
mount -t sysfs sys sys/
mount -o bind /dev dev/
chroot .

11. Cross fingers, reboot

reboot

Find symlinks on Cpanel

Posted on by Randy

Find all possible root symlinks (leftover from attempted exploits) and save them as a list ‘symlinks.txt’.

ls /var/cpanel/users | grep -v "\`\|\.\|cpanel\|root\|mysql\|nobody" | \
while read CPUSER; do find /home/$CPUSER -type l -not \( -lname "/home/$CPUSER/*" \
-o -lname "*rvsitebuilder*" -o -lname "[^/]*" -o -lname "/usr/local/apache/domlogs/*" \
-o -lname "/usr/local/urchin/*" \) ; done \
> symlinks.txt &

Simple Monitoring with Email Alerts that works on LSI MegaRAID and Adaptec

Posted on by Randy

This tool will poll the output of command(s) or URL(s), and send email alerts if the output changes, contains (or not contains) certain text, or becomes unavailable. It’s a light weight, reliable monitoring replacement for the pile of garbage most RAID vendors include with their cards. Complex excludes and finds can be specified as Perl regex patterns — useful for suppression various noise (RAID verify, ect). The default configuration includes examples that will monitor local LSI or Adaptec cards.

Note – Tested on CentOS only. if someone wants to try Alien on Debian please let me know how it works.

rpm -ivh http://djlab.com/stuff/cloud-mon-1.1-3.i686.rpm

After installation, edit /etc/cloud.ini then:

service cloud-mon restart

Make sure you have logrotate installed to prevent log growth. This package includes a simple logrotate script.

Winsplit Revolution (Like Windows Snap but for Multiple Displays)

Posted on by Randy

I just added a 4th monitor to my office PC and finally admitted to needing help with window placement, far beyond Windows 7’s limited snap feature, this tool really gets the job done:

http://www.winsplit-revolution.com/

It’s a free, light-weight ‘snap’ on steroids designed specifically for multi-display setups.

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Guest isolation in XenServer 6.1 / XCP 1.6

Posted on by Randy

Since XenServer 6.1 (XCP 1.6) there is a new feature that allows you to lock VIF to specific MAC and IP addresses. This is nice (and also very buggy!), but it doesn’t provide any security other than keeping VMs from stealing each others IPs. A better solution should allow to (optionally) isolate traffic between groups of VMs as well. For example, prevent users from accessing other users VMs over a common private/backend network, but allow communication between VMs in the same group and with external networks.

Step 1: We must relocate the VIF locking data into the VM’s vm-data store, similar to how security groups are managed by Nova (openstack). This lets us use more fields and options.

Step 2: Patch /opt/xensource/libexec/setup-vif-rules to fix *several* bugs as well as take an extra locking mode (isolated). In isolate mode, VMs can only communicate to IPs in the allowed list. Use a common set of IPs on each set of VMs in the same ‘security group’ and your various groups of guests are isolated from each other.

Step 3: Patch another bug in /etc/xensource/scripts/vif to prevent orphaned rules from piling up in openvswitch when VMs are restarted.

Patches are here:

http://djlab.com/stuff/xs61/setup-vif-rules.patch
http://djlab.com/stuff/xs61/vif.patch

This will only work with openvswitch networking mode and has been tested on XS 6.1 and XCP 1.6. Do not try it in bridged mode (you shouldn’t be using bridged mode anyways).

XenServer multipath configuration for LIO targets

Posted on by Randy

XenServer multipath.conf with special support for LIO-based iSCSI targets to maximize multipath performance and ensures 100% stability. path_grouping_policy setting doesn’t seem to matter (between group_by_prio and multibus) in most basic setups. Invalid lines (as reported by XenServer 6.1) have also been removed.

http://djlab.com/stuff/xs61/multipath.conf

Specifically:

        device {
                vendor "LIO-ORG"
                product "*"
                path_grouping_policy group_by_prio
                path_checker tur
                getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
                prio_callout "/sbin/mpath_prio_alua /dev/%n"
                path_selector "round-robin 0"
                hardware_handler "1 alua"
                rr_weight uniform
                rr_min_io 2
                failback immediate
        }

Migrate a XenServer VM without a Pool or Shared Storage

Posted on by Randy

Source is now in github, please help me make it better! If you just want a 32-bit binary (to run on Dom0), download it from here instead.

With the help of Ben Booth’s Xen::API (Perl module) I put together a VM migration script to export a VM directly to another host with no intermediary file. The transfer occurs over XAPI with no temp files or local disk interaction. This script can run directly on the source or destination host, or any server in between. Bear in mind, you will have the best speeds and least network overhead running this directly on the destination host.

As of today, MigrateVM has been tested and works fine on XenServer 5.6 through 6.5.

Options:

-sh : source host
-su : source user (usually root)
-sp : source pass
-sv : source VM label or UUID
-dh : destination host
-du : destination user
-dp : destination pass
-ds : destination SR (optional)

If any of the options are omitted, you will be prompted for them.

Example output:

[root@cl-ash-h1 ~]# ./migratevm
Enter source host name/IP (blank = localhost): 1.2.3.4
Enter username for 1.2.3.4 (blank = root):
Enter password for 1.2.3.4: ************
Enter source vm name or uuid on 1.2.3.4: my_vm
Enter destination host name/IP (blank = localhost):
Enter username for localhost (blank = root):
Enter password for localhost: ******
Destination SR on localhost (blank for default):
Starting transfer
...................    12.0%, 30618.43 (KB/sec)
Done.

Download the script like this:

wget http://djlab.com/stuff/migratevm-1.0.2.tar.gz
tar zxf migratevm-1.0.2.tar.gz && cd migratevm-1.0.2
./migratevm

If you get ‘bad ELF’ or something like that on a 64 bit system, try to install 32-bit glibc, for example:

Older XenServers: yum install glibc.i686
XenServer 6.5:  yum install glibc.i686 --enablerepo=base --enablerepo=updates --disablerepo=citrix

Binary and source are both included in the tarball.

Version 1.0.2 has an updated binary build which should now run on XenServer 6.5. We needed to static link expat into the binary because it is no longer installed by default on XS 6.5.