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annotate SMALL @ 37:0913e2ee3545

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we're nearly there yet
author Matt Johnston <matt@ucc.asn.au>
date Fri, 30 Jul 2004 03:02:19 +0000
parents fe6bca95afa7
children b9d3f725e00b
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1 Tips for a small system:
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2
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3 The following are set in options.h
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4
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5 - You can safely disable blowfish and twofish ciphers, and MD5 hmac, without
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6 affecting interoperability
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7
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8 - If you're compiling statically, you can turn off host lookups
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10 - You can disable either password or public-key authentication, though note
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11 that the IETF draft states that pubkey authentication is required.
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13 - Similarly with DSS and RSA, you can disable one of these if you know that
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14 all clients will be able to support a particular one. The IETF draft
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15 states that DSS is required, however you may prefer to use RSA.
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16 DON'T disable either of these on systems where you aren't 100% sure about
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17 who will be connecting and what clients they will be using.
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19 - Disabling the MOTD code and SFTP-SERVER may save a small amount of codesize
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21 - You can disable x11, tcp and agent forwarding as desired. None of these are
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22 essential, although agent-forwarding is often useful even on firewall boxes.
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23
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24 If you are compiling statically, you may want to disable zlib, as it will use
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25 a few tens of kB of binary-size (./configure --disable-zlib).
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27 You can create a combined binary, see the file MULTI, which will put all
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28 the functions into one binary, avoiding repeated code.
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30 If you're compiling with gcc, you might want to look at gcc's options for
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31 stripping unused code. The relevant vars to set before configure are:
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33 LDFLAGS=-Wl,--gc-sections
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34 CFLAGS="-ffunction-sections -fdata-sections"
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35
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36 You can also experiment with optimisation flags such as -Os, note that in some
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37 cases these flags actually seem to increase size, so experiment before
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38 deciding.
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39
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40 Of course using small C libraries such as uClibc and dietlibc can also help.
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41
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42 If you have any queries, mail me and I'll see if I can help.