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54 lines
2.0 KiB
Plaintext
54 lines
2.0 KiB
Plaintext
Tips for a small system:
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If you only want server functionality (for example), compile with
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make PROGRAMS=dropbear
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rather than just
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make dropbear
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so that client functionality in shared portions of Dropbear won't be included.
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The same applies if you are compiling just a client.
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---
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The following are set in options.h:
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- You can safely disable blowfish and twofish ciphers, and MD5 hmac, without
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affecting interoperability
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- If you're compiling statically, you can turn off host lookups
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- You can disable either password or public-key authentication, though note
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that the IETF draft states that pubkey authentication is required.
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- Similarly with DSS and RSA, you can disable one of these if you know that
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all clients will be able to support a particular one. The IETF draft
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states that DSS is required, however you may prefer to use RSA.
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DON'T disable either of these on systems where you aren't 100% sure about
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who will be connecting and what clients they will be using.
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- Disabling the MOTD code and SFTP-SERVER may save a small amount of codesize
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- You can disable x11, tcp and agent forwarding as desired. None of these are
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essential, although agent-forwarding is often useful even on firewall boxes.
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---
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If you are compiling statically, you may want to disable zlib, as it will use
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a few tens of kB of binary-size (./configure --disable-zlib).
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You can create a combined binary, see the file MULTI, which will put all
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the functions into one binary, avoiding repeated code.
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If you're compiling with gcc, you might want to look at gcc's options for
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stripping unused code. The relevant vars to set before configure are:
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LDFLAGS=-Wl,--gc-sections
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CFLAGS="-ffunction-sections -fdata-sections"
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You can also experiment with optimisation flags such as -Os, note that in some
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cases these flags actually seem to increase size, so experiment before
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deciding.
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Of course using small C libraries such as uClibc and dietlibc can also help.
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If you have any queries, mail me and I'll see if I can help.
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