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TCP connection resets on PIX 501

 
 
Crumb
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      10-12-2006
Hi,

I have to start by saying sorry for asking for help as I am not a Cisco
guy and have no Cisco knowledge

A work for a company that is using A VoIP application across two sites
connected via Cisco PIX 501

For the most of the time every thing is working fine but from time to
time we get one way transmission on the handsets. The VoIP vendor is
saying the problem is due to the PIX configuration but my maintainer of
the PIX units is not the best and seems to not know what he is doing.

Here is what the VoIP vendor is saying:

The phones establish an H323 connection at logon time through which the
mediastreaming is switched on/off on call activity on the phone. The
special thing is here, that the RTP/RTCP ports that are negotiated at
logon time are always used by the phone over all calls. The Phone
controller relies on this behavior of the phones. The traceline
indicates that the H323 negotiation (done in the context of a call)
returned ports that are different of the ports negotiated at logon
time.

The typical failure on the user interface is that the phone cannot
hear, but is heard by the peer.

The H323 connection maintains two TCP connections between Phone
controller and phone. What you see with the Pix VPN is that this device
monitors and controls TCP connections such that a TCP connection is
terminated after a certain time with no traffic on that connection. The
PIX firewall sends in that case TCP RESET packets to both sides of the
TCP connection. The Phone Controller immediately reestablishes the
associated H323 connection and find the phone wants to use different
ports.

You can configure the PIX firewall to not do terminate the TCP
connections.

Here is the running configuration on the PIX

PIX Version 6.3(5)
interface ethernet0 100full
interface ethernet1 100full
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password encrypted
passwd encrypted
hostname PIX15
domain-name ****************.co.uk
fixup protocol dns maximum-length 512
fixup protocol ftp 21
no fixup protocol h323 h225 1720
no fixup protocol h323 ras 1718-1719
fixup protocol http 80
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol sip 5060
fixup protocol sip udp 5060
fixup protocol skinny 2000
fixup protocol smtp 25
fixup protocol sqlnet 1521
fixup protocol tftp 69
no names
access-list 120 permit ip 192.168.8.0 255.255.255.0 192.168.15.0
255.255.255.0
access-list 130 permit ip 192.168.8.0 255.255.255.0 192.168.17.0
255.255.255.0
access-list 140 permit ip 192.168.8.0 255.255.255.0 192.168.16.0
255.255.255.0
access-list 150 permit ip 192.168.8.0 255.255.255.0 192.168.18.0
255.255.255.0
access-list 100 permit ip 192.168.8.0 255.255.255.0 192.168.15.0
255.255.255.0
access-list 100 permit ip 192.168.8.0 255.255.255.0 192.168.17.0
255.255.255.0
access-list 100 permit ip 192.168.8.0 255.255.255.0 192.168.16.0
255.255.255.0
access-list 100 permit ip 192.168.8.0 255.255.255.0 192.168.18.0
255.255.255.0
pager lines 24
logging on
logging host outside 80.229.XXX.XXX
mtu outside 1500
mtu inside 1500
ip address outside XXX.XXX.XXX.XXX 255.255.255.252
ip address inside 192.168.8.151 255.255.255.0
ip audit info action alarm
ip audit attack action alarm
pdm location 192.168.8.150 255.255.255.255 inside
pdm location 192.168.8.254 255.255.255.255 inside
pdm location XXX.XXX.XXX.XXX 255.255.255.255 outside
pdm location 192.168.7.0 255.255.255.0 outside
pdm location 192.168.15.0 255.255.255.0 outside
pdm location 192.168.16.0 255.255.255.0 outside
pdm location 192.168.17.0 255.255.255.0 outside
pdm location 192.168.18.0 255.255.255.0 outside
pdm location 192.168.3.0 255.255.255.0 inside
pdm history enable
arp timeout 14400
global (outside) 1 172.16.8.153 netmask 255.255.255.0
nat (inside) 0 access-list 100
nat (inside) 1 0.0.0.0 0.0.0.0 0 0
route outside 0.0.0.0 0.0.0.0 82.118.108.61 1
timeout xlate 3:00:00
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225
1:00:00
timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout sip-disconnect 0:02:00 sip-invite 0:03:00
timeout uauth 0:05:00 absolute
aaa-server TACACS+ protocol tacacs+
aaa-server TACACS+ max-failed-attempts 3
aaa-server TACACS+ deadtime 10
aaa-server RADIUS protocol radius
aaa-server RADIUS max-failed-attempts 3
aaa-server RADIUS deadtime 10
aaa-server LOCAL protocol local
http server enable
http 192.168.8.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
sysopt connection permit-ipsec
sysopt connection permit-pptp
crypto ipsec transform-set myset esp-des esp-md5-hmac
crypto map newmap 20 ipsec-isakmp
crypto map newmap 20 match address 120
crypto map newmap 20 set peer 82.118.103.66
crypto map newmap 20 set transform-set myset
crypto map newmap 30 ipsec-isakmp
crypto map newmap 30 match address 130
crypto map newmap 30 set peer 82.118.103.60
crypto map newmap 30 set transform-set myset
crypto map newmap 40 ipsec-isakmp
crypto map newmap 40 match address 140
crypto map newmap 40 set peer 82.118.125.2
crypto map newmap 40 set transform-set myset
crypto map newmap 50 ipsec-isakmp
crypto map newmap 50 match address 150
crypto map newmap 50 set peer 62.121.30.21
crypto map newmap 50 set transform-set myset
crypto map newmap interface outside
isakmp enable outside
isakmp key ******** address XXX.XXX.XXX.XXX 66 netmask 255.255.255.255
no-xauth no-config-mode
isakmp key ******** address .XXX.XXX.XXX netmask 255.255.255.255
no-xauth no-config-mode
isakmp key ******** address .XXX.XXX.XXX netmask 255.255.255.255
no-xauth no-config-mode
isakmp key ******** address .XXX.XXX.XXX netmask 255.255.255.255
no-xauth no-config-mode
isakmp identity address
isakmp policy 10 authentication pre-share
isakmp policy 10 encryption des
isakmp policy 10 hash md5
isakmp policy 10 group 1
isakmp policy 10 lifetime 1000
telnet 192.168.8.254 255.255.255.255 inside
telnet 192.168.8.150 255.255.255.255 inside
telnet timeout 5
ssh .XXX.XXX.XXX 255.255.255.255 outside
ssh 192.168.8.0 255.255.255.0 inside
ssh 192.168.3.0 255.255.255.0 inside
ssh timeout 60
console timeout 0
vpdn group 1 accept dialin pptp
vpdn group 1 ppp authentication mschap
vpdn group 1 ppp encryption mppe 40 required
vpdn group 1 pptp echo 60
vpdn group 1 client authentication local
vpdn username s****l password *********
vpdn enable outside
terminal width 132
Cryptochecksum:
: end
[OK]
PIX15#


Can someone help me as I am now desperate


Regards

Crumb

 
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