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Port Forwarding smtp through CISCO PIX506e Due to Slow email delivery

Posted on 2008-10-15
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Last Modified: 2013-11-30
Hi All,

I'm having an issue at a customers site where they are experiencing slow inbound email.  Unfortunatley the ISP provider can not help until I can allow their support guys to telnet on port 25 into the email server.  The Cisco 506e router currently only allows smtp port forwarding on a specific IP range which contains the ISP forwarding email servers and spam filter.

Do You think I should allow ANY IP address to have access/port forward smtp into the email server or should i allow just the Support guys ip range and keep the current range open? Can you provide me we the appropiate config to configure the pix for all IP and just one IP to port forward from the PIX to the Private IP of the Email server

I currently not on site but will be back first thing tommorow and will implement changes then.

The Client setup is basic and consists of the following:

The cisco pix 506e Outside IP address is = 87.xxx.xxx.162
The cisco pix 506e Inside IP address is = 10.0.0.254
The Internet Router which the 506e sits behind  = 87.xxx.xxx.161
The email server IP = 10.0.0.200

#################
IP RANGE of FORWARDING EMAIL SERVERS
195.40.1.0
212.135.6.0
##############
Is an old IP and should be deleted 87.xxx.xxx.34
Is an old IP and should be deleted 87.xxx.xxx.33

##### cisco current config########


PIX Version 6.3(4)
interface ethernet0 auto
interface ethernet1 auto
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password 8Ry2YjIyt7RRXU24 encrypted
passwd 2KFQnbNIdI.2KYOU encrypted
hostname PIX506E
domain-name ciscopix.com
fixup protocol dns maximum-length 512
fixup protocol ftp 21
fixup protocol h323 h225 1720
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
names
 
 
access-list 100 permit icmp any any time-exceeded 
access-list 100 remark Webflow
access-list 100 permit tcp any interface outside eq www 
access-list 100 permit tcp host 213.xxx.xxx.146 host 87.xxx.xxx.162 range ftp ssh 
access-list 100 permit tcp host 213.xxx.xxx.146 host 87.xxx.xxx.33 eq www 
access-list 100 permit icmp any host 87.xxx.xxx.162 echo-reply 
access-list 100 permit tcp host 213.xxx.xxx.146 host 87.xxx.xxx.33 eq 1000 
access-list 100 permit tcp host 213.xxx.xxx.146 host 87.xxx.xxx.34 eq 1000 
access-list 100 permit tcp 195.40.1.0 255.255.255.0 host 87.xxx.xxx.162 eq smtp 
access-list 100 permit tcp 212.135.6.0 255.255.255.0 host 87.xxx.xxx.162 eq smtp 
access-list 100 permit tcp 195.40.1.0 255.255.255.0 host 87.xxx.xxx.161 eq smtp 
access-list 100 permit tcp 212.135.6.0 255.255.255.0 host 87.xxx.xxx.161 eq smtp 
access-list 100 permit tcp host 65.xxx.xxx.80 host 87.xxx.xxx.162 eq 1863 
access-list 100 permit tcp host 216.xxx.xxx.169 host 87.xxx.xxx.34 eq 5050 
access-list 100 permit tcp any eq smtp interface outside eq smtp 
 
 
access-list 101 permit ip 10.0.0.0 255.255.255.0 10.0.1.0 255.255.255.0 
access-list split1 permit ip 10.0.0.0 255.255.255.0 10.0.1.0 255.255.255.0 
 
 
pager lines 24
logging on
logging timestamp
logging trap debugging
logging host inside 89.0.0.91
mtu outside 1500
mtu inside 1500
ip address outside 87.xxx.xxx.162 255.255.255.240
ip address inside 10.0.0.254 255.255.255.0
 
ip audit info action alarm
ip audit attack action alarm
ip local pool COMPANYvpnpool 10.0.1.1-10.0.1.25
pdm location 10.0.0.200 255.255.255.255 inside
pdm location 10.0.0.220 255.255.255.255 inside
pdm location 195.40.1.0 255.255.255.0 outside
pdm location 212.135.6.0 255.255.255.0 outside
pdm location 213.253.45.146 255.255.255.255 outside
pdm location 65.54.239.80 255.255.255.255 outside
pdm location 1o.0.1.0 255.255.255.0 outside
pdm location 216.155.193.169 255.255.255.255 outside
pdm location 10.0.91 255.255.255.255 inside
pdm location 87.xxx.xxx.161 255.255.255.255 inside
pdm location 87.xxx.xxx.162 255.255.255.255 inside
 
 
 
 
pdm logging debugging 100
pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list 101
nat (inside) 1 0.0.0.0 0.0.0.0 0 0
static (inside,outside) tcp interface ftp 10.0.0.220 ftp netmask 255.255.255.255 0 0 
static (inside,outside) tcp interface ssh 10.0.0.220 ssh netmask 255.255.255.255 0 0 
static (inside,outside) tcp interface www 10.0.0.220 www netmask 255.255.255.255 0 0 
static (inside,outside) tcp interface 1000 10.0.0.220 1000 netmask 255.255.255.255 0 0 
static (inside,outside) tcp interface smtp 10.0.0.200 smtp netmask 255.255.255.255 500 500 
static (inside,outside) 10.0.0.254 10.0.0.254 netmask 255.255.255.255 0 0 
static (inside,outside) 87.xxx.xxx.161 87.xxx.xxx.161 netmask 255.255.255.255 0 0 
access-group 100 in interface outside
route outside 0.0.0.0 0.0.0.0 87.xxx.xxx.161 1
timeout xlate 0:05:00
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 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 10.0.0.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
sysopt connection permit-ipsec
crypto ipsec transform-set mediaset esp-3des esp-md5-hmac 
crypto dynamic-map dynmap 90 set transform-set mediaset
crypto map newmap 20 ipsec-isakmp dynamic dynmap
crypto map newmap client configuration address respond
crypto map newmap interface outside
isakmp enable outside
isakmp identity address
isakmp nat-traversal 15
isakmp policy 10 authentication pre-share
isakmp policy 10 encryption 3des
isakmp policy 10 hash md5
isakmp policy 10 group 2
isakmp policy 10 lifetime 86400
vpngroup COMPANYvpngroup address-pool COMPANYvpnpool
vpngroup COMPANYvpngroup dns-server 10.0.0.200
vpngroup COMPANYvpngroup default-domain COMPANYltd.local
vpngroup COMPANYvpngroup split-tunnel split1
vpngroup COMPANYvpngroup idle-time 28800
vpngroup COMPANYvpngroup max-time 28800
vpngroup COMPANYvpngroup password ********
telnet 10.0.0.0 255.255.255.0 inside
telnet 10.0.0.200 255.255.255.255 inside
 
telnet timeout 60
ssh timeout 5
console timeout 0
terminal width 80
Cryptochecksum:526a32bfd8619baac9867cb63ef7e565
: end
[OK]

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Question by:Firewall_Help
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3 Comments
 
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Accepted Solution

by:
lrmoore earned 250 total points
ID: 22725793
For testing, you can change this:

>access-list 100 permit tcp any eq smtp interface outside eq smtp

to this:
access-list 100 permit tcp any interface outside eq smtp

For email to come in, the source port will not be 25, only the destination is 25

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Author Comment

by:Firewall_Help
ID: 22726140
will the below port forward smtp from any inbound IP? Whats the actual meaning of the below? So email from any host emailed to my cisco pix outside ip will  be forwarded to my email server 10.0.0.200 using the below?

access-list 100 permit tcp any interface outside eq smtp
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LVL 79

Expert Comment

by:lrmoore
ID: 22726222
The actual port forwarding is done with the static:
 >static (inside,outside) tcp interface smtp 10.0.0.200 smtp netmask 255.255.255.255

The access-list entry will allow inbound smtp from "anywhere"

once you complete troubleshooting with the ISP, you can remove that single line and be back to allowing inbound SMTP only from recognized/authorized hosts.

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