201 lines
3.9 KiB
HTML
201 lines
3.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>( SMTP Relay ) - Internal MASQed computers cannot send SMTP or POP-3 mail!</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Linux IP Masquerade HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Frequently Asked Questions"
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HREF="faq.html"><LINK
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REL="PREVIOUS"
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TITLE="( Stops working ) - IP MASQ works fine for a while but then it stops working. A reboot
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seems to fix this. Why?"
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HREF="masq-stops-working.html"><LINK
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REL="NEXT"
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TITLE="( Source Routing ) - I need different internal MASQed networks to exit
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on different external IP addresses"
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HREF="iproute2.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux IP Masquerade HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="masq-stops-working.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 7. Frequently Asked Questions</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="iproute2.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="SMTP"
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></A
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>7.38. ( SMTP Relay ) - Internal MASQed computers cannot send SMTP or POP-3 mail!</H1
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><P
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>
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Though this isn't a Masquerading issue but many users do this so it should be
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mentioned. </P
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><P
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>SMTP: The issue is that you are probably using your Linux box as an SMTP
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relay server and get the following error:</P
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><P
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> <TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>"error from mail server: we do not relay"</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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Newer versions of Sendmail and other Mail Transfer Agents (MTAs) disable
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relaying by default (this is a good thing). So do the following to fix this:</P
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><P
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> <P
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></P
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><UL
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><LI
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><P
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>Sendmail: Enable specific relaying for your internal MASQed machines by editing
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the /etc/sendmail.cw file and add the hostname and domain name of your internal
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MASQed machine. You should also check to see that the /etc/hosts file has the
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IP address and Fully Qualified Domain Name (FQDN) configured in it. Once this
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is done, you need to restart Sendmail for it to re-read its configuration
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files. This is covered in
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<A
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HREF="http://www.ecst.csuchico.edu/~dranch/LINUX/index-linux.html#TrinityOS"
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TARGET="_top"
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>TrinityOS - Section 25</A
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> </P
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></LI
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></UL
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> </P
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><P
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>POP-3: Some users configure their internal MASQ'ed computer's POP-3 clients to
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connect to some external SMTP server. While this is fine, many SMTP servers
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out there will try to IDENT your connection on port 113. Most likely your
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problem stems around your default Masquerade policy being set to DENY. This is
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BAD. Set it to REJECT and re-run your rc.firewall-* ruleset.</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="masq-stops-working.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="iproute2.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>( Stops working ) - IP MASQ works fine for a while but then it stops working. A reboot
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seems to fix this. Why?</TD
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><TD
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
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HREF="faq.html"
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>( Source Routing ) - I need different internal MASQed networks to exit
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on different external IP addresses</TD
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></TR
|
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></TABLE
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></DIV
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></BODY
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></HTML
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> |