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Diffstat (limited to 'SMALL')
| -rw-r--r-- | SMALL | 53 |
1 files changed, 53 insertions, 0 deletions
@@ -0,0 +1,53 @@ +Tips for a small system: + +If you only want server functionality (for example), compile with + make PROGRAMS=dropbear +rather than just + make dropbear +so that client functionality in shared portions of Dropbear won't be included. +The same applies if you are compiling just a client. + +--- + +The following are set in options.h: + + - You can safely disable blowfish and twofish ciphers, and MD5 hmac, without + affecting interoperability + + - If you're compiling statically, you can turn off host lookups + + - You can disable either password or public-key authentication, though note + that the IETF draft states that pubkey authentication is required. + + - Similarly with DSS and RSA, you can disable one of these if you know that + all clients will be able to support a particular one. The IETF draft + states that DSS is required, however you may prefer to use RSA. + DON'T disable either of these on systems where you aren't 100% sure about + who will be connecting and what clients they will be using. + + - Disabling the MOTD code and SFTP-SERVER may save a small amount of codesize + + - You can disable x11, tcp and agent forwarding as desired. None of these are + essential, although agent-forwarding is often useful even on firewall boxes. + +--- + +If you are compiling statically, you may want to disable zlib, as it will use +a few tens of kB of binary-size (./configure --disable-zlib). + +You can create a combined binary, see the file MULTI, which will put all +the functions into one binary, avoiding repeated code. + +If you're compiling with gcc, you might want to look at gcc's options for +stripping unused code. The relevant vars to set before configure are: + +LDFLAGS=-Wl,--gc-sections +CFLAGS="-ffunction-sections -fdata-sections" + +You can also experiment with optimisation flags such as -Os, note that in some +cases these flags actually seem to increase size, so experiment before +deciding. + +Of course using small C libraries such as uClibc and dietlibc can also help. + +If you have any queries, mail me and I'll see if I can help. |