UNIX BUILD NOTES

Some notes on how to build Bitcoin in Unix.

To Build

./autogen.sh
./configure
make

This will build bitcoin-qt as well if the dependencies are met. See readme-qt.md for more information.

Dependencies

Library Purpose Description

libssl SSL Support Secure communications libdb4.8 Berkeley DB Blockchain & wallet storage libboost Boost C++ Library miniupnpc UPnP Support Optional firewall-jumping support

miniupnpc may be used for UPnP port mapping. It can be downloaded from here. UPnP support is compiled in and turned off by default. See the configure options for upnp behavior desired:

--with-miniupnpc         No UPnP support miniupnp not required
--disable-upnp-default   (the default) UPnP support turned off by default at runtime
--enable-upnp-default    UPnP support turned on by default at runtime

IPv6 support may be disabled by setting:

--disable-ipv6           Disable IPv6 support

Licenses of statically linked libraries: Berkeley DB New BSD license with additional requirement that linked software must be free open source Boost MIT-like license miniupnpc New (3-clause) BSD license

Versions used in this release:
GCC 4.3.3
OpenSSL 1.0.1c
Berkeley DB 4.8.30.NC
Boost 1.37
miniupnpc 1.6

Dependency Build Instructions: Ubuntu & Debian

Build requirements:

sudo apt-get install build-essential
sudo apt-get install libssl-dev

for Ubuntu 12.04:

sudo apt-get install libboost-all-dev

db4.8 packages are available here.

Ubuntu precise has packages for libdb5.1-dev and libdb5.1++-dev, but using these will break binary wallet compatibility, and is not recommended.

for other Ubuntu & Debian:

sudo apt-get install libdb4.8-dev
sudo apt-get install libdb4.8++-dev
sudo apt-get install libboost1.37-dev

(If using Boost 1.37, append -mt to the boost libraries in the makefile)

Optional:

sudo apt-get install libminiupnpc-dev (see --with-miniupnpc and --enable-upnp-default)

Notes

The release is built with GCC and then "strip bitcoind" to strip the debug symbols, which reduces the executable size by about 90%.

miniupnpc

tar -xzvf miniupnpc-1.6.tar.gz
cd miniupnpc-1.6
make
sudo su
make install

Berkeley DB

You need Berkeley DB 4.8. If you have to build Berkeley DB yourself:

../dist/configure --enable-cxx
make

Boost

If you need to build Boost yourself:

sudo su
./bootstrap.sh
./bjam install

Security

To help make your bitcoin installation more secure by making certain attacks impossible to exploit even if a vulnerability is found, binaries are hardened by default. This can be disabled with:

./configure --enable-hardening

Hardening enables the following features:

Position Independent Executable Build position independent code to take advantage of Address Space Layout Randomization offered by some kernels. An attacker who is able to cause execution of code at an arbitrary memory location is thwarted if he doesn't know where anything useful is located. The stack and heap are randomly located by default but this allows the code section to be randomly located as well.

On an Amd64 processor where a library was not compiled with -fPIC, this will cause an error such as: "relocation R_X86_64_32 against `......' can not be used when making a shared object;"

To test that you have built PIE executable, install scanelf, part of paxutils, and use:
```
  scanelf -e ./bitcoin
```
The output should contain: TYPE ET_DYN
Non-executable Stack If the stack is executable then trivial stack based buffer overflow exploits are possible if vulnerable buffers are found. By default, bitcoin should be built with a non-executable stack but if one of the libraries it uses asks for an executable stack or someone makes a mistake and uses a compiler extension which requires an executable stack, it will silently build an executable without the non-executable stack protection.

To verify that the stack is non-executable after compiling use: scanelf -e ./bitcoin

the output should contain: STK/REL/PTL RW- R-- RW-

The STK RW- means that the stack is readable and writeable but not executable.

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