All this data from IBM TCP/IP Guide, tcpguide.hlp file (c) by IBM.
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 SOCKS support is configured in these files: 

      SOCKS.ENV defines the SOCKS defaults, including whether SOCKS support 
       is on or off. 

      SOCKS.CFG defines the SOCKS servers and the direct connections to 
       hosts in your private business network. 
  
  TCP/IP for OS/2 does not provide the SOCKS configuration files. If you want 
  to use SOCKS support, you can create these files using the Configuration 
  notebook or you can manually create them. 

  These files must reside in the directory specified by the ETC environment 
  variable. 

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 The format of the SOCKS.ENV file is: 

   SOCKS_FLAG flag
   SOCKS_DOMAIN domain
   SOCKS_NS name_server
   SOCKS_SERVER
   SOCKS_USER user
   SOCKS_PASSWORD password
   

  SOCKS_FLAG flag 
            Specifies whether the SOCKS support is being used. flag is set to 
            ON or OFF. This keyword and parameter are required. 

  SOCKS_DOMAIN domain 
            Specifies the domain of your private business network. domain is 
            the domain name, such as ibm.com. This keyword and parameter 
            are required. 

  SOCKS_NS name_server 
            Specifies the SOCKS nameserver for resolving Internet names that 
            are outside of your private business network. name_server is the IP 
            address or name of the nameserver, such as 100.45.20.0 or 
            nameserver.ibm.com. This keyword and parameter are required. 

  SOCKS_SERVER 
            This keyword is required for internal use. You should not add to, 
            change, or delete this line. 

  SOCKS_USER user 
            Specifies your SOCKS user ID. user is the user ID registered on the 
            SOCKS server, such as socksid. The SOCKS_USER keyword is 
            required. The user parameter, however, can be optional; check with 
            your system administrator to see if it is required. 

  SOCKS_PASSWORD password (encrypted) 
            Specifies your SOCKS password used for authentication. The 
            SOCKS_PASSWORD keyword is required. 
  
  Notes: 

    1. Comments are not allowed in the SOCKS.CFG file. 

    2. The password field is an enhancement provided by the currently upgraded 
       Version 5 of SOCKS client protocol as a means to support user 
       authentication. The password is encrypted before it is written onto this 
       file. Hence, this file cannot be edited directly to enter the password. 
  
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 The format of the SOCKS.CFG file is: 

   direct d_host d_mask
   sockd @=socks_server s_host s_mask *=s_userid *=s_password
   

  direct d_host d_mask 
            Defines a direct connection to a host in your private business 
            network, where: 

            d_host         Is the IP address (in 32-bit dotted-decimal notation) 
                           of the host (or hosts, depending on the subnet mask 
                           used) for which the direct connection is being defined. 

            d_mask         Is the subnet mask, in 32-bit dotted-decimal 
                           notation, to apply against d_host. 

  sockd @=socks_server s_host s_mask 
            Defines a SOCKS server on your LAN, where: 

            socks_server   Is the host name or IP address (in 32-bit 
                           dotted-decimal notation) of the server, such as 
                           socksserv. 

            s_host         Is the IP address (in 32-bit dotted-decimal notation) 
                           of the host (or hosts, depending on the subnet mask 
                           used) that can be reached through this SOCKS server. 

            s_mask         Is the subnet mask, in 32-bit dotted-decimal 
                           notation, to apply against s_host 

            s_userid       Is the SOCKS userid. This is the user id that is 
                           registered on the SOCKS server. It consists of 1 to 
                           255 characters. 

            s_password     Is the SOCKS password used for authentication. The 
                           password is encrypted before it is written to the 
                           socks.cfg file. 
  
  
  Notes: 

    1. You can include multiple direct and sockd statements in the SOCKS.CFG 
       file, but all direct statements must precede all sockd statements. 
       Statements are processed in the order in which they appear in the file. 

    2. Comments are not allowed in the SOCKS.CFG file. 

    3. The Version 4 of SOCKS client protocol has been upgraded to    Version 
       5 (SOCKS5) client protocol. This version of SOCKS provides    
       username/password authentication. 
