Cisco IOS capture lazy dog

# create a buffer
monitor capture buffer buffer1 size 512 max-size 512 circular

# create a capture point
monitor capture point ip cef capture1 FastEthernet 0/1/3 both

# associate capture with the buffer 'buffer1'
monitor capture point associate capture1 buffer1

# Start monitor the capture
monitor capture point start capture1

# Show the buffer
show monitor capture buffer buffer1 dump

# Stop the capture
monitor capture point stop capture1

dns blacklist bash script

LISTS="sbl-xbl.spamhaus.org zen.spamhaus.org bl.spamcop.net dnsbl.njabl.org b.barracudacentral.org dnsbl.sorbs.net pbl.spamhaus.org"
HOSTS="1.2.3.4 127.0.0.1"

for list in $LISTS
do
for host in $HOSTS
do
W=$( echo ${host} | cut -d. -f1 )
X=$( echo ${host} | cut -d. -f2 )
Y=$( echo ${host} | cut -d. -f3 )
Z=$( echo ${host} | cut -d. -f4 )
result=`dig +short $Z.$Y.$X.$W.$list`
if [ "$result" != "" ]; then
echo "$host listed in $list"
fi
done
done

Passive OS fingerprint, smartphone detection

I recently started a service that allows smartphone users to connect to one of my networks over PPTP to hide their origins. To ensure users are not trying to use the service on computers, I figured some passive OS fingerprinting would be in place.

p0f -i ppp0
p0f - passive os fingerprinting utility, version 2.0.8
(C) M. Zalewski , W. Stearns
p0f: listening (SYN) on 'ppp0', 262 sigs (14 generic, cksum 0F1F5CA2), rule: 'all'.

# Iphone 3GS, iOS 4.1
10.100.200.100:52900 - UNKNOWN [65535:64:1:64:M1404,N,W2,N,N,T,S,E:P:?:?] (up: 121 hrs)
-> 1.2.3.4:80 (link: unknown-1444).

# android 2.2, HTC Desire
10.100.200.100:48885 - UNKNOWN [S44:64:1:60:M1356,S,T,N,W1:.:?:?] (NAT!) (up: 3 hrs)
-> 1.2.3.4:80 (link: unknown-1396)

syslog-ng by example

1) make sure udp listener is on
netstat -anop|grep 514

2) If not, add udp(); as source to syslog-ng.conf

# udp source
source s_udp {
udp();
};

3) create a destination
destination d_name { file("/var/log/file.log"); };

4) create a filter
filter f_name {
host("192.168.123.123")
and facility(auth,authpriv);
};

5) Create the logging for the filter to the destination
log {
source(s_udp);
filter(f_name);
destination(d_name);
};

Do add the remote logging on the servers, if needed tcpdump on the syslog-ng server to verify that log entries come in.

Narrowing down processes using loads of disk I/O

iostat shows you the reads and writes

# iostat -m
Linux 2.6.28-11-generic (rant-e-minor) 12/04/2009 _i686_ (2 CPU)

avg-cpu: %user %nice %system %iowait %steal %idle
9.20 0.01 2.76 1.10 0.00 87.02

Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda 8.26 0.19 0.03 3443 642
sda1 8.25 0.19 0.03 3442 642
sda2 0.00 0.00 0.00 0 0
sda5 0.00 0.00 0.00 0 0


Enable block dump to see which processes writes data, and then tail the kern.log or equivalent:

# echo 1 > /proc/sys/vm/block_dump
# tail -f /var/log/kern.log
Dec 4 14:09:33 rant-e-minor kernel: [18343.000899] kjournald(772): WRITE block 237973000 on sda1
Dec 4 14:09:33 rant-e-minor kernel: [18343.000902] kjournald(772): WRITE block 237973008 on sda1
Dec 4 14:09:33 rant-e-minor kernel: [18343.000905] kjournald(772): WRITE block 237973016 on sda1
Dec 4 14:09:33 rant-e-minor kernel: [18343.001365] kjournald(772): WRITE block 237973024 on sda1
Dec 4 14:09:37 rant-e-minor kernel: [18346.074288] wpa_supplicant(7871): dirtied inode 8742018 (wpa_supplicant.log) on sda1
Dec 4 14:09:37 rant-e-minor kernel: [18346.074297] wpa_supplicant(7871): dirtied inode 8742018 (wpa_supplicant.log) on sda1
Dec 4 14:09:37 rant-e-minor kernel: [18346.074299] wpa_supplicant(7871): dirtied inode 8742018 (wpa_supplicant.log) on sda1

Don't forget to 'echo 0 > /proc/sys/vm/block_dump'