Oct 01 2010

Troubleshoot and Monitor Traffic on PIX/ASA

Published by at 11:36 pm under Cisco

How to troubleshoot traffic going through your PIX or ASA firewall while response times are extremely slow, bandwidth flat-lining or unusually high, or download speeds down to 0?

Access Lists Statistics

If you filter incoming traffic with access lists, you may get a quick overview of what kind of traffic is coming through your firewall.

cisco_pix# show access-list acl_in
access-list acl_in; 17 elements
access-list acl_in line 1 permit tcp any any eq domain (hitcnt=7)
access-list acl_in line 2 permit udp any any eq domain (hitcnt=40379)
access-list acl_in line 3 permit tcp any any eq www (hitcnt=157103)
access-list acl_in line 4 permit tcp any any eq 8080 (hitcnt=466)
access-list acl_in line 5 permit tcp any any eq https (hitcnt=1910)
access-list acl_in line 6 permit tcp any any eq ftp (hitcnt=2)
access-list acl_in line 7 permit tcp any any eq smtp (hitcnt=550)
access-list acl_in line 8 permit tcp any any eq pop3 (hitcnt=14660)

You can reset hit numbers in configuration mode to get the latest statistics:

cisco_pix# configure terminal
cisco_pix(config)# clear access-list acl_in counters



You can also display each PIX interface global traffic. You’re better off resetting data to get accurate results.

cisco_pix# clear traffic

Give it a few minutes to collect the data.

cisco_pix# show traffic
        received (in 9.570 secs):
                133 packets     19918 bytes
                13 pkts/sec     2081 bytes/sec
        transmitted (in 9.570 secs):
                199 packets     22997 bytes
                20 pkts/sec     2403 bytes/sec
        received (in 9.570 secs):
                158 packets     14392 bytes
                16 pkts/sec     1503 bytes/sec
        transmitted (in 9.570 secs):
                102 packets     14264 bytes
                10 pkts/sec     1490 bytes/sec


Type of Traffic

You can display the number of connections per second for each type of traffic:

cisco_pix# show perfmon

PERFMON STATS:    Current      Average
Xlates               0/s          0/s
Connections          0/s          0/s
TCP Conns            0/s          0/s
UDP Conns            0/s          0/s
URL Access           0/s          0/s
URL Server Req       0/s          0/s
TCP Fixup           27/s          1/s
TCPIntercept         0/s          0/s
HTTP Fixup           5/s          2/s
FTP Fixup            0/s          0/s
AAA Authen           0/s          0/s
AAA Author           0/s          0/s
AAA Account          0/s          0/s



Display the current and maximum number of connections:

cisco_pix# show conn count
35 in use, 195 most used

Or going deeper into details with each established connection:

cisco_pix# show conn
33 in use, 195 most used
TCP out in idle 0:00:32 Bytes 19354 flags UIO
TCP out in idle 0:03:49 Bytes 156840 flags UIO

Useful since it shows the amount of tranfered bytes for each connection.

Memory and Processor

Pay attention to your memory and CPU resources indeed

cisco_pix# show cpu usage
CPU utilization for 5 seconds = 2%; 1 minute: 2%; 5 minutes: 6%

cisco_pix# show memory
Free memory:         5069344 bytes
Used memory:        11707872 bytes
-------------     ----------------
Total memory:       16777216 bytes


Ongoing Monitoring

Many tools are available out there to measure and graph interface traffic. You can detect something is wrong only if you can compare with previous data. Graphs are the best way to achieve this.
Among the most popular tools, I’ve retained Cacti, MRTG as well as Smokeping. Smokeping lets you graph and check links latency.

You can get more information on this online on Cisco documentation.

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