vpn server on EC2 Ubuntu

I followed instruction on Setting up a VPN-server on Amazon EC2 up to this line:

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Then need to configure /etc/ppp/pptpd-options as:

#refuse-pap
#refuse-chap
#refuse-mschap
require-chap
#require-mschap-v2
#require-mppe-128




Following Configuring a PPTP-VPN on iOS and Android
Make to disable encryption or choose no encryption

If connects well,
tail -f /var/log/syslog should look like:

Jan 2 03:23:30 ip-10-138-31-87 pptpd[6570]: CTRL: Client ???.93.139.47 control connection started
Jan 2 03:23:31 ip-10-138-31-87 pptpd[6570]: CTRL: Starting call (launching pppd, opening GRE)
Jan 2 03:23:31 ip-10-138-31-87 pppd[6571]: Plugin /usr/lib/pptpd/pptpd-logwtmp.so loaded.
Jan 2 03:23:31 ip-10-138-31-87 pppd[6571]: pppd 2.4.5 started by root, uid 0
Jan 2 03:23:31 ip-10-138-31-87 pppd[6571]: Using interface ppp0
Jan 2 03:23:31 ip-10-138-31-87 pppd[6571]: Connect: ppp0 <--> /dev/pts/2
Jan 2 03:23:31 ip-10-138-31-87 pptpd[6570]: GRE: Bad checksum from pppd.
Jan 2 03:23:31 ip-10-138-31-87 pppd[6571]: Warning - secret file /etc/ppp/chap-secrets has world and/or group access
Jan 2 03:23:32 ip-10-138-31-87 pppd[6571]: Deflate (15) compression enabled
Jan 2 03:23:32 ip-10-138-31-87 pppd[6571]: Cannot determine ethernet address for proxy ARP
Jan 2 03:23:32 ip-10-138-31-87 pppd[6571]: local IP address 192.168.0.1
Jan 2 03:23:32 ip-10-138-31-87 pppd[6571]: remote IP address 192.168.0.234

Errors were encountered while processing: procps

There seems to be problem with installing procps.

dpkg -i --force-all /var/cache/apt/archives/procps_1%3a3.2.8-9ubuntu3_amd64.deb
(Reading database ... 30892 files and directories currently installed.)
Preparing to replace procps 1:3.2.8-9ubuntu3 (using .../procps_1%3a3.2.8-9ubuntu3_amd64.deb) ...
Unpacking replacement procps ...
Setting up procps (1:3.2.8-9ubuntu3) ...
start: Job failed to start
dpkg: error processing procps (--install):
subprocess installed post-installation script returned error exit status 1
Processing triggers for man-db ...
Errors were encountered while processing:
procps

The solution for me is to remove the package from /var/cache/apt/archives/procps_1%3a3.2.8-9ubuntu3_amd64.deb
and downloaded a newer verion from http://debomatic64.debian.net/natty/aptcache/procps_1%253a3.2.8-9ubuntu5_amd64.deb

then dpkg -i procps_1%3a3.2.8-9ubuntu3_amd64.deb installation was successful.

/etc/alternatives/-->Debian alternatives system

Where is location of java on ubuntu?
Finding out the answer is not just use "whereis java" or "which java":

The alternatives directory lead to the alternative concept. when you type java, it could refer to a different real java location if a new version has just installed.
Eg. I was using java 5, typing java would start JVM 5; after installing java 6, type java would start JVM6.

Intuitively, I think having this extra level of indirection is useless...