ASA 5505 drops internet/outside interface intermittently

[adamcolliss]

Hi
We are having some issues with our Cisco ASA 5505 unit, it intermittently drops the outside interface connection. From the internal network all appears to be working correctly, but no traffic is passed outside and no internet traffic can reach the outside interface.
We've tried the firewall on two different sites, both sites were fine with their old firewalls so I don't think it's a connection issue. We've also tried upgrading the firmware of the 5505.
The line drops intermittently, sometimes it will stay up for a couple of weeks, other times it drops every couple of days. There appears to be no pattern. Our ISP has checked our line and reports no problems.

Any help greatly appreciated.

Config below


!
ASA Version 7.2(3)
!
hostname ******
domain-name *************
enable password ************************* encrypted
names
!
interface Vlan1
nameif inside
security-level 100
ip address 192.168.1.1 255.255.255.0
!
interface Vlan2
nameif outside
security-level 0
ip address *************** *****************
!
interface Vlan3
shutdown
nameif dmz
security-level 50
ip address 192.192.192.1 255.255.255.0
!
interface Ethernet0/0
switchport access vlan 2
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Ethernet0/4
!
interface Ethernet0/5
!
interface Ethernet0/6
!
interface Ethernet0/7
!
passwd ******************** encrypted
ftp mode passive
clock timezone GMT/BST 0
clock summer-time GMT/BDT recurring last Sun Mar 1:00 last Sun Oct 2:00
dns server-group DefaultDNS
domain-name fw.jetset.local
access-list JS_splitTunnelAcl standard permit any
access-list inside_nat0_outbound extended permit ip any 192.168.1.192 255.255.255.224
access-list inside_nat0_outbound extended permit ip 192.168.1.0 255.255.255.0 172.16.0.0 255.255.0.0
access-list outside_access_in extended permit icmp host ****************** interface outside
access-list outside_1_cryptomap extended permit ip 192.168.1.0 255.255.255.0 172.16.0.0 255.255.0.0
pager lines 24
logging enable
logging asdm debugging
mtu inside 1500
mtu outside 1500
mtu dmz 1500
ip local pool Local_IP_Pool 192.168.1.200-192.168.1.220 mask 255.255.255.0
no failover
monitor-interface inside
monitor-interface outside
monitor-interface dmz
icmp unreachable rate-limit 1 burst-size 1
asdm image disk0:/asdm-523.bin
no asdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list inside_nat0_outbound
nat (inside) 1 0.0.0.0 0.0.0.0
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 ********************* 1
timeout xlate 3:00:00
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 uauth 0:05:00 absolute
http server enable
http **************** 255.255.255.255 outside
http 192.168.1.0 255.255.255.0 inside
http **************** 255.255.255.255 outside
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
telnet timeout 5
ssh timeout 5
console timeout 0
dhcpd auto_config outside
!
dhcpd address 192.168.1.80-192.168.1.90 inside
dhcpd dns ***************** ***************** interface inside
dhcpd enable inside
!

!
class-map inspection_default
match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
parameters
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
!
service-policy global_policy global

 

[CRS1]

I had the same issue with my ASA5505. Every 30 days or so it dropped the Internet connection, everything on the inside network worked fine. I upgraded the IOS and ASDM to the latest with the same issue, I finally cleared the entire configuration on the firewall, I erased everything and started from scratch. I configured the ASA line by line using the CLI with a simple config. After the 30 days went by I started to add more to the config. To make a long story short I added all the configs to the ASA and I've had it running without dropping the Internet connection for over 60 days. I do experience the problem that it drops http-server therefore I can't use the ASDM unless I reboot. I have tried to troubleshoot that and I'm not sure what the issue could be. If I keep on having this problem I will RMA my ASA with Cisco. It's a bit annoying having ASDM dropping for no reason. The PIX 501 I used worked Flawless!!! Never had one issue with it. We'll see...So I say clear the config on it and start over line by line. At the end of the day I don't know what was causing my Internet to drop for no reason. It appears I don't have the problem anymore.

 

[desperado618]

At the time that there are connectivity issues, does a packet capture show anything coming to/from that interface? Does a "show arp | grep <default gw ip>" appear correct? Does your ISP router also show an arp entry for your firewall? I have seen this issue on BGP and EIGRP networks.

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[DJRabin]

I'm also experiencing this issue but with a higher frequency. The outside interface stays up for anywhere from a few minutes to 10 or 15 hours but then access from LAN to WAN is lost (though interface status shows as up.)

I was having issues with DNS inspection dropping packets over 512 bits but have corrected this issue with a custom policy map that drops when the size is over 1500.

I did notice a bunch of syslog entries that looked like this after the outside interface stopped passing internet traffic:

6 Aug 13 2008 18:51:01 106015 10.0.0.122 223.1.1.128 Deny TCP (no connection) from 10.0.0.122/139 to 223.1.1.128/3727 flags SYN ACK on interface inside

I'm stumped... Running config is below, any help is appreciated!

________________________________________________
interface Vlan1
nameif inside
security-level 100
ip address 10.0.0.140 255.255.255.0
!
interface Vlan2
nameif outside
security-level 0
ip address PUBLIC_IP 255.255.255.248
!
interface Ethernet0/0
switchport access vlan 2
!
interface Ethernet0/1
!
interface Ethernet0/2
!
interface Ethernet0/3
!
interface Ethernet0/4
!
interface Ethernet0/5
!
interface Ethernet0/6
!
interface Ethernet0/7
!
passwd *************** encrypted
ftp mode passive
dns server-group DefaultDNS
domain-name default.domain.invalid
access-list outside_access_in extended permit tcp any interface outside eq www
access-list outside_access_in extended permit tcp any interface outside eq ftp
access-list outside_access_in extended permit tcp any interface outside eq smtp
access-list outside_access_in extended permit tcp any interface outside eq pop3
access-list inside_access_in extended permit ip 10.0.0.0 255.255.255.0 any
access-list inside_access_in extended permit tcp any host 10.0.0.161 eq www
access-list PCIVPN_splitTunnelAcl standard permit any
access-list inside_nat0_outbound extended permit ip any 10.0.0.240 255.255.255.240
pager lines 24
logging enable
logging asdm informational
mtu inside 1500
mtu outside 1500
ip local pool VPNpool 10.0.0.241-10.0.0.254 mask 255.255.255.0
icmp unreachable rate-limit 1 burst-size 1
asdm image disk0:/asdm-522.bin
no asdm history enable
arp timeout 14400
nat-control
global (outside) 1 interface
nat (inside) 0 access-list inside_nat0_outbound
nat (inside) 1 10.0.0.0 255.255.255.0
static (inside,outside) tcp interface smtp 10.0.0.141 smtp netmask 255.255.255.255
static (inside,outside) tcp interface

http://www 10.0.0.161

http://www netmask

255.255.255.255
static (inside,outside) tcp interface pop3 10.0.0.123 pop3 netmask 255.255.255.255
static (inside,outside) tcp interface ftp 10.0.0.161 ftp netmask 255.255.255.255
access-group inside_access_in in interface inside
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 209.104.227.185 1
timeout xlate 3:00:00
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 uauth 0:05:00 absolute


!
class-map inspection_default
match default-inspection-traffic
!
!
policy-map type inspect dns preset_dns_map
parameters
message-length maximum 512
policy-map type inspect dns DNS_1500bit_packet
parameters
message-length maximum 1500
policy-map global_policy
class inspection_default
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 dns DNS_1500bit_packet
!
service-policy global_policy global



-DJ
ACA-I, Convergence+, Net+ A+

 

[DJRabin]

Thought I'd add, inbound access to the outside interface also becomes unavailable; POP, HTTP/S fail to connect to the internal servers.

Thanks!

-DJ
ACA-I, Convergence+, Net+ A+

 

[desperado618]

Dr,
Your issue appears to be an MTU limitation. VPN traffic is encapsulated so there is additional overhead on a packet that may be pushing it over the standard 1500 MTU limit on most interfaces.

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In plain English

 

[desperado618]

Correction,
I just reread your post and it appears that your DNS issue has been resolved. At the time when you are having these problems through the tunnel, is there an actuall Phase II SA built (sh crypto ipsec sa peer <ip>)? If so, does it show both encaps and decaps? May want to turn up the debug level (debug crypto ipsec 215). Depending on the amount of VPN traffic, you may need to send the output to file.

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IT Security news and information
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