SMTP through PIX 506E

[TimRaines]

I am absolutely stumped. I cannot get inbound SMTP traffic to come through the firewall. I can send SMTP out. I can get

http://www traffic,

pop3 traffic.....you name it. But port 25 will NOT allow traffic in. I've tried telnet to port 25, but no response. When I switch the ports so that SMTP responds on port 80 and

http://www responds

on port 25, SMTP traffic (via Telnet) gets through fine and

http://www traffic

is blocked. I'm 99.9999% sure it's my PIX.

Please someone help me. I'm pulling all my hair out and my wife is ready to file for divorce.

Here's my config:

PIX Version 6.2(1)
nameif ethernet0 outside security0
nameif ethernet1 inside security100
enable password 01TWMwmP6LBPFwj7 encrypted
passwd 01TWMwmP6LBPFwj7 encrypted
hostname pix
domain-name whatever.com
clock timezone GMT 0
fixup protocol ftp 21
fixup protocol http 80
fixup protocol h323 h225 1720
fixup protocol h323 ras 1718-1719
fixup protocol ils 389
fixup protocol rsh 514
fixup protocol rtsp 554
fixup protocol sqlnet 1521
fixup protocol sip 5060
fixup protocol skinny 2000
no fixup protocol smtp 25
names
access-list outside_access_in permit icmp any any echo-reply
access-list outside_access_in permit icmp any any time-exceeded
access-list outside_access_in permit icmp any host 99.99.99.4
access-list outside_access_in permit tcp any host 99.99.99.4 eq smtp
access-list outside_access_in permit tcp any host 99.99.99.4 eq www
access-list VPNUsers_splitTunnelAcl permit ip 10.1.2.0 255.255.255.0 any
access-list inside_outbound_nat0_acl permit ip any 10.1.2.0 255.255.255.0
access-list outside_cryptomap_dyn_20 permit ip any 10.1.2.0 255.255.255.0
pager lines 24
logging on
interface ethernet0 auto
interface ethernet1 auto
icmp deny any outside
mtu outside 1500
mtu inside 1500
ip address outside 99.99.99.2 255.255.255.248
ip address inside 10.1.1.1 255.255.255.0
ip audit info action alarm
ip audit attack action alarm
ip local pool VPNPool 10.1.2.2-10.1.2.254
pdm location 10.1.1.4 255.255.255.255 inside
pdm logging informational 100
pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list inside_outbound_nat0_acl
nat (inside) 1 0.0.0.0 0.0.0.0 0 0
static (inside,outside) 99.99.99.4 10.1.1.4 netmask 255.255.255.255 0 0
access-group outside_access_in in interface outside
route outside 0.0.0.0 0.0.0.0 99.99.99.1 1
timeout xlate 0:05:00
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h323 0:05:00 si
p 0:30:00 sip_media 0:02:00
timeout uauth 0:05:00 absolute
aaa-server TACACS+ protocol tacacs+
aaa-server RADIUS protocol radius
aaa-server LOCAL protocol local
ntp authenticate
ntp server 192.5.41.41 source outside
ntp server 192.5.41.40 source outside
ntp server 192.5.41.209 source outside
http server enable
http 0.0.0.0 0.0.0.0 outside
http 10.1.1.0 255.255.255.0 inside
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
sysopt connection permit-ipsec
no sysopt route dnat
crypto ipsec transform-set ESP-DES-SHA esp-des esp-sha-hmac
crypto dynamic-map outside_dyn_map 20 match address outside_cryptomap_dyn_20
crypto dynamic-map outside_dyn_map 20 set transform-set ESP-DES-SHA
crypto map outside_map 65535 ipsec-isakmp dynamic outside_dyn_map
crypto map outside_map interface outside
isakmp enable outside
isakmp policy 20 authentication pre-share
isakmp policy 20 encryption des
isakmp policy 20 hash sha
isakmp policy 20 group 2
isakmp policy 20 lifetime 86400
vpngroup VPNUsers address-pool VPNPool
vpngroup VPNUsers dns-server 10.1.1.2
vpngroup VPNUsers wins-server 10.1.1.2
vpngroup VPNUsers default-domain whatever.com
vpngroup VPNUsers split-tunnel VPNUsers_splitTunnelAcl
vpngroup VPNUsers pfs
vpngroup VPNUsers idle-time 1800
vpngroup VPNUsers password ********
telnet 0.0.0.0 0.0.0.0 inside
telnet timeout 5
ssh timeout 5
username Admin password FEXeBaknPHfjSGh6 encrypted privilege 15
terminal width 80
Cryptochecksum:4cf442e95e4c86632233b0b39ab25561

 

[ceindaco]

Two things:

First, did you on purpose disable the fixup protocol for SMTP?. That is the one that allows returning traffic for your mail gateway.

If you enable that FIXUP feature, you will get all incoming traffic as a response from your requests, without the need of specifying an access-list.

Second, Are you sure the port on which your gateway will receive incoming traffic as a result of the SMTP request is 25?. Your server may go on a different port when sending SMTP traffic and you are blocking it by specifying port SMTP.

My suggestions:

1. Enable fixup protocol SMTP 25
2. Verify the port on which your server is talking to the outside, source port not destination port.

 

[TimRaines]

Yes. I did disable the fixup on purpose. I've read in a number of places that the mailguard "feature" causes a lot of problems for MS Exchange users, so I thought I'd take that out of the equation (at least for now).

I think I figured it out. And I'm pretty embarrassed about it. The telnet client I was using was from a local college. I was telnetting in to their server and then telnetting (or attempting to) back in to mine on port 25. I called my ISP to see if they're blocking SMTP traffic, and they're not. I never bothered to check to see if the local college was.

I tried telnet from another place and got in fine and dandy. Three days of my time (and the time of everyone who read this and tried to help me) was wasted. My apologies to all.

The only thing stupider I could have done, I'd imagine, was to have unplugged the server from the wall.