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Shorewall: accepting SSH access from certain IP-addresses only

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 these policies set up in /etc/shorewall/policy:

#SOURCE         DEST            POLICY          LOG LEVEL net             $FW             DROP            info net             loc             DROP            info net             all             DROP            info

which I think is pretty much standard (note: I’m leaving out empty columns at the end). Now, I needed a rule in /etc/shorewall/rules to make an exception from these default policies:

#ACTION         SOURCE                DEST                  PROTO   DEST #                                                                   PORT ACCEPT          net:XXX.XXX.XXX.XXX   $FW                   tcp     ssh

where XXX is the IP address of the machine at work. Now, that (somewhat to my surprise) didn’t quite work. I could now see my home machine from the work machine (i.e. the SSH request was rejected rather than dropped), but I wasn’t allowed in. The reason is of course that when you use IP masquerading, the system needs to know where to route incoming connections to. So a second rule in /etc/shorewall/rules was needed:

DNAT            net:XXX.XXX.XXX.XXX   loc:YYY.YYY.YYY.YYY   tcp     ssh

…and

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 vi /etc/shorewall/rules 

#SECTION NEW

DNS/ACCEPT      $FW             net

DNS/ACCEPT      loc             net

NTP/ACCEPT      $FW             net

##WEBMIN

ACCEPT          net               $FW     tcp     10000

ACCEPT          loc               $FW     tcp     10000

## Accept connections from the Internet to the Server

#ACCEPT          net             $FW             tcp     21

#ACCEPT          $FW             net             tcp     21

#### FTP

FTP(ACCEPT)     net:10.10.0.0/16                $FW

FTP(ACCEPT)     net:172.16.0.0/16               $FW

FTP(ACCEPT)     net:203.82.192.0/20             $FW

FTP(ACCEPT)     net:202.22.192.0/20             $FW

FTP(ACCEPT)     net:175.29.0.0/16               $FW

FTP(ACCEPT)     net:203.76.144.0/20             $FW

FTP(ACCEPT)     net:202.161.176.0/20            $FW

## For SSH

SSH(ACCEPT)     net             $FW

# Make ping work

#

ACCEPT          fw        loc           icmp    8

ACCEPT          loc       fw            icmp    8

ACCEPT          fw        net           icmp    8

ACCEPT          net       fw            icmp    8

# For NTP , Shakil

NTP(ACCEPT)     net:10.10.0.0/16                $FW

NTP(ACCEPT)     net:172.16.0.0/16               $FW

NTP(ACCEPT)     net:203.82.192.0/20             $FW

NTP(ACCEPT)     net:202.22.192.0/20             $FW

NTP(ACCEPT)     net:175.29.0.0/16               $FW

NTP(ACCEPT)     net:203.76.144.0/20             $FW

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