Cisco ASA 5505-trouble after weekend

[brettpenza]

We've got a Cisco ASA 5505 firewall in a high school setting.  About 600 users internally.  The network is usually running fine.  However, on Mondays, or this week Tuesday (after a 3 day weekend) the firewall gets very hard to find.  Since it is the only access to the internet, most users are denied access.  I can't even ping the firewall on most of the clients, though it is occasionally accessible.   All the equipment appears fine.  I try rebooting the switches and firewall.   Sometimes it gets me a few minutes of up time.   Through all of this difficulty, there is no problem accessing information internally (server folders and files, client signons, all fine).  

Strangely,  the next day (after I'm ready to start buying replacement equipment)  everything is working fine again.  

Someone told me that I should check the logs and go from there.  I will do that tomorrow (if I can connect again), but does this make any sense to anyone?   

How could a problem which appears so dire, become completely resolved the next day?  

Thanks.

[Tinashe Ndhlovu]

Just sharing my two cents here but the symptoms of the issue you have presented seem to indicate the usual duplicate IP rogue router issue.. when the issue occurs run an arp -a from a machine that cannot get to the internet and compare the MAC address to that of your firewalls internal interface.. or try and replicate the issue your self.. configure 10.0.0.1 which believe me is a very common IP address on some machine and test.. chances are someone is plugging in some device with the same IP as your firewall and causing random intermittent outages.. that's just my two cents... ok maybe three cents.. ;)

[brettpenza]

Genius Tinashe .. Genius.

It took me a while to finally realize it, but this is exactly what is happening.  A mobile device has apparently got my Cisco Firewall IP. 

How did you best get around this?

Did you just reconfig the Firewall to something like 10.0.0.9 or something? 

Or is it possible to prevent duplication on the Firewall?  

I am already holding 10.0.0.1 - 99 outside of my DHCP (HANDLED BY MY WINDOWS SERVER) 

So, any mobile device that joins the network should be obtaining a DHCP from my server. 

But apparently this is not happening.  

Thanks for any suggestions.

[paul driver]

Hello

sounds like you could have a possible infection on the network?

Are you able to monitor the lan to internet traffic traffic produce a capture - or even apply basic ip accounting to see if any specific host is causing this?

If not then another possible thing to do is-

apply a constant ping to an Internet address from your lan core and then one by one disconnect/reconnect  the access interconnects to each closet as the same time check the internet connection it  may be a way of manually tracking down a Probmatic device to a certain area - then from that area do the same until you reach the root cause

res

paul

[Tinashe Ndhlovu]

My money is still on random user duplicate IP hehe 

[brettpenza]

All of this info was very , very helpful.  

But it certainly does appear that the DUPLICATE IP is the true problem. 

I just checked the arp -a for a client that was working fine :

10.0.0.1 -  44-2b-03   ...    which is cisco.

A client with no access  

10.0.0.1  - 64-bc-0c      which is a mobile device. !!!!!!

So, my question is.  

how do I get the ASA to prevent anyone from duplicating its Firewall internal address.

I guess I could just rename the firewall to something like  10.0.0.9  or something..

The thing is that these addresses (10.0.0.1-99) are all outside of the Microsoft Server DHCP POOL. 

So, I am wondering how the mobile device was able to maintain itself as 10.0.0.1.   It should have picked up a DHCP ADDRESS from my server.

Weird stuff. 

Any advice on how best to proceed. 

Thanks. 

-

[brettpenza]

I do  appreciate all the assistance here.   Unfortunately, we are still not up and running consistently. 

I have been running  show xlate, clear xlate,  show conn,  clear conn.   

I have taken suspicious ip's and added them to a group host to block both in and out.  But that is like treading water with a teaspoon.

The show conn count is just creeping up way too fast.  I am a novice, but we go from 0 - thousands in a few minutes.  Then the internet access shuts down.    I clear the connections and we can work again for a few minutes.   Is this normal?   

See the current config below.   This is obviously very frustrating.  Not sure how we went from 100% uptime to this.  We are a school setting with about 600 people.  Why are we getting thousands of connections grinding to a halt?   I have blocked all incoming and still the count grows. 

Thanks for any suggestions.  

-

Result of the command: "show conf"

: Saved
: Written by enable_15 at 11:19:01.383 EST Mon Nov 6 2017
!
ASA Version 9.1(4)
!
hostname ciscoasa
domain-name hnedu.com
enable password mnpTCRVkk1.ZjiWJ encrypted
xlate per-session deny tcp any4 any4
xlate per-session deny tcp any4 any6
xlate per-session deny tcp any6 any4
xlate per-session deny tcp any6 any6
xlate per-session deny udp any4 any4 eq domain
xlate per-session deny udp any4 any6 eq domain
xlate per-session deny udp any6 any4 eq domain
xlate per-session deny udp any6 any6 eq domain
passwd 2KFQnbNIdI.2KYOU encrypted
names
ip local pool VPNUsers 10.0.0.80-10.0.0.99 mask 255.255.0.0
!
interface Ethernet0/0
switchport access vlan 2
speed 100
duplex full
!
interface Ethernet0/1
speed 100
duplex full
!
interface Ethernet0/2
speed 100
duplex full
!
interface Ethernet0/3
speed 100
duplex full
!
interface Ethernet0/4
speed 100
duplex full
!
interface Ethernet0/5
speed 100
duplex full
!
interface Ethernet0/6
!
interface Ethernet0/7
!
interface Vlan1
nameif inside
security-level 100
ip address 10.0.0.1 255.255.0.0
!
interface Vlan2
description External Connection
nameif outside
security-level 0
ip address 209.117.123.226 255.255.255.224
!
boot system disk0:/asa914-k8.bin
ftp mode passive
clock timezone EST -5
clock summer-time EDT recurring
dns domain-lookup inside
dns domain-lookup outside
dns server-group DefaultDNS
name-server 10.0.0.2
name-server 10.0.0.4
domain-name hnedu.com
same-security-traffic permit inter-interface
same-security-traffic permit intra-interface
object network obj-10.0.0.0
subnet 10.0.0.0 255.255.0.0
object network obj-10.0.0.64
subnet 10.0.0.64 255.255.255.192
object network obj-10.0.0.90-papagino
host 10.0.0.90
object network obj_any
subnet 0.0.0.0 0.0.0.0
object network Host-to-Block
host 69.172.201.153
description malware
object network 69.172.201.153
host 69.172.201.153
description malwaresite
object network 23.111.134.37
host 23.111.134.37
object network 97.107.139.41
host 97.107.139.41
object network 17.173.254.222
host 17.173.254.222
object network 45.199.134.223
host 45.199.134.223
object-group network RDP_static
object-group service RemoteDesktop tcp-udp
description Windows Remote Desktop Access
port-object eq 3389
object-group protocol TCPUDP
protocol-object udp
protocol-object tcp
object-group network Host-To-Block
description Blocking malware sites
network-object object 69.172.201.153
network-object object 23.111.134.37
network-object object 97.107.139.41
network-object object 17.173.254.222
network-object object 45.199.134.223
access-list inside_access_in extended permit ip any4 any4
access-list outside extended permit tcp any4 host 10.0.1.33 eq 3389
access-list Napoleons_splitTunnelAcl standard permit 10.0.0.0 255.255.0.0
access-list inside_nat0_outbound extended permit ip 10.0.0.0 255.255.0.0 10.0.0.64 255.255.255.192
access-list outside_access_in extended deny ip object-group Host-To-Block any
access-list outside_access_in extended permit tcp any4 host 10.0.0.90 eq www inactive
access-list outside_access_in extended permit icmp any any
access-list inside_access_in_1 extended deny ip any object Host-to-Block
access-list inside_access_in_1 extended permit ip any any
access-list Outside_IN extended deny ip object-group Host-To-Block any
access-list Outside_IN extended deny ip any any
pager lines 24
logging enable
logging asdm informational
mtu inside 1500
mtu outside 1500
icmp unreachable rate-limit 1 burst-size 1
asdm image disk0:/asdm-715-100.bin
no asdm history enable
arp timeout 14400
no arp permit-nonconnected
nat (inside,any) source static obj-10.0.0.0 obj-10.0.0.0 destination static obj-10.0.0.64 obj-10.0.0.64 no-proxy-arp route-lookup
!
object network obj-10.0.0.90-papagino
nat (inside,outside) static 209.117.123.227
object network obj_any
nat (inside,outside) dynamic interface
access-group inside_access_in in interface inside control-plane
access-group inside_access_in_1 in interface inside
access-group Outside_IN in interface outside
route outside 0.0.0.0 0.0.0.0 209.117.123.225 1
timeout xlate 3:00:00
timeout pat-xlate 0:00:30
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00
timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00
timeout sip-provisional-media 0:02:00 uauth 0:05:00 absolute
timeout tcp-proxy-reassembly 0:01:00
timeout floating-conn 0:00:00
dynamic-access-policy-record DfltAccessPolicy
user-identity default-domain LOCAL
http server enable
http 192.168.1.0 255.255.255.0 inside
http 10.0.0.0 255.255.0.0 inside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart warmstart
crypto ipsec ikev1 transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
crypto ipsec ikev1 transform-set ESP-AES-256-MD5 esp-aes-256 esp-md5-hmac
crypto ipsec ikev1 transform-set ESP-DES-SHA esp-des esp-sha-hmac
crypto ipsec ikev1 transform-set ESP-DES-MD5 esp-des esp-md5-hmac
crypto ipsec ikev1 transform-set ESP-AES-192-MD5 esp-aes-192 esp-md5-hmac
crypto ipsec ikev1 transform-set ESP-3DES-MD5 esp-3des esp-md5-hmac
crypto ipsec ikev1 transform-set ESP-AES-256-SHA esp-aes-256 esp-sha-hmac
crypto ipsec ikev1 transform-set ESP-AES-128-SHA esp-aes esp-sha-hmac
crypto ipsec ikev1 transform-set ESP-AES-192-SHA esp-aes-192 esp-sha-hmac
crypto ipsec ikev1 transform-set ESP-AES-128-MD5 esp-aes esp-md5-hmac
crypto ipsec security-association pmtu-aging infinite
crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set pfs group1
crypto dynamic-map SYSTEM_DEFAULT_CRYPTO_MAP 65535 set ikev1 transform-set ESP-AES-128-SHA ESP-AES-128-MD5 ESP-AES-192-SHA ESP-AES-192-MD5 ESP-AES-256-SHA ESP-AES-256-MD5 ESP-3DES-SHA ESP-3DES-MD5 ESP-DES-SHA ESP-DES-MD5
crypto map outside_map 65535 ipsec-isakmp dynamic SYSTEM_DEFAULT_CRYPTO_MAP
crypto map outside_map interface outside
crypto ca trustpoint _SmartCallHome_ServerCA
crl configure
crypto ca trustpool policy
crypto ca certificate chain _SmartCallHome_ServerCA
certificate ca 6ecc7aa5a7032009b8cebcf4e952d491
308205ec 308204d4 a0030201 0202106e cc7aa5a7 032009b8 cebcf4e9 52d49130
0d06092a 864886f7 0d010105 05003081 ca310b30 09060355 04061302 55533117
30150603 55040a13 0e566572 69536967 6e2c2049 6e632e31 1f301d06 0355040b
13165665 72695369 676e2054 72757374 204e6574 776f726b 313a3038 06035504
0b133128 63292032 30303620 56657269 5369676e 2c20496e 632e202d 20466f72
20617574 686f7269 7a656420 75736520 6f6e6c79 31453043 06035504 03133c56
65726953 69676e20 436c6173 73203320 5075626c 69632050 72696d61 72792043
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30303230 38303030 3030305a 170d3230 30323037 32333539 35395a30 81b5310b
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3130312f 302d0603 55040313 26566572 69536967 6e20436c 61737320 33205365
63757265 20536572 76657220 4341202d 20473330 82012230 0d06092a 864886f7
0d010101 05000382 010f0030 82010a02 82010100 b187841f c20c45f5 bcab2597
a7ada23e 9cbaf6c1 39b88bca c2ac56c6 e5bb658e 444f4dce 6fed094a d4af4e10
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7f432657 5833833b 330a17b0 d04e9124 ad867d64 12dc744a 34a11d0a ea961d0b
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69676e2e 636f6d2f 76736c6f 676f2e67 69663028 0603551d 11042130 1fa41d30
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6c2527b9 deb78458 c61f381e a4c4cb66
quit
crypto ikev1 enable outside
crypto ikev1 policy 10
authentication pre-share
encryption 3des
hash sha
group 2
lifetime 86400
telnet timeout 5
ssh timeout 5
ssh key-exchange group dh-group1-sha1
console timeout 0
management-access inside
vpn-addr-assign local reuse-delay 5

dhcp-client update dns server none
dhcpd dns 10.0.0.2 10.0.0.4
dhcpd wins 10.0.0.2 10.0.0.4
dhcpd domain hnedu.com!
!
dhcpd option 5 ip 10.0.0.2 10.0.0.4 interface inside
dhcpd option 6 ip 10.0.0.2 10.0.0.4 interface inside
!
dhcprelay server 10.0.0.2 inside
dhcprelay server 10.0.0.4 inside
threat-detection basic-threat
threat-detection scanning-threat shun duration 3600
threat-detection statistics host number-of-rate 2
threat-detection statistics port
threat-detection statistics protocol
threat-detection statistics access-list
threat-detection statistics tcp-intercept rate-interval 30 burst-rate 400 average-rate 200
group-policy Napoleons internal
group-policy Napoleons attributes
wins-server value 10.0.0.2 10.0.0.4
dns-server value 10.0.0.2 10.0.0.4
vpn-tunnel-protocol ikev1
split-tunnel-policy tunnelspecified
split-tunnel-network-list value Napoleons_splitTunnelAcl
default-domain value hnedu.com
username bpenza password LTg/b/c3kPWfC8KM encrypted privilege 0
username bpenza attributes
vpn-group-policy Napoleons
username baudette password nPZIRfshkE7WcaDQ encrypted
username baudette attributes
vpn-group-policy Napoleons
tunnel-group Napoleons type remote-access
tunnel-group Napoleons general-attributes
address-pool VPNUsers
default-group-policy Napoleons
tunnel-group Napoleons ipsec-attributes
ikev1 pre-shared-key *****
!
class-map inspection_default
match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
parameters
message-length maximum client auto
message-length maximum 512
policy-map global_policy
class inspection_default
inspect dns preset_dns_map
inspect ftp
inspect h323 h225
inspect h323 ras
inspect rsh
inspect rtsp
inspect esmtp
inspect sqlnet
inspect skinny
inspect sunrpc
inspect xdmcp
inspect sip
inspect netbios
inspect tftp
inspect ip-options
inspect icmp
class class-default
user-statistics accounting
inspect icmp
set connection conn-max 2500 embryonic-conn-max 1500 per-client-max 2500
set connection timeout embryonic 0:40:00 half-closed 0:20:00 idle 0:20:00 dcd 0:00:01 5
!
service-policy global_policy global
prompt hostname context
call-home reporting anonymous
hpm topN enable
Cryptochecksum:0f04ccd297c33c10c4b9e4cbd0e72bff