越狱又开始了，没周末总要下一个看看。之前用 delug，速度还行，用起来感觉不错。可是自从 1.0rc 的某个版本之后，下载的时候时不时出现 CPU 100% 的情况。就装了 transmisstion，他不支持 dht，国内的下载速度很慢，去下国外的好像还行。
今天又试了一下 rtorrent，之前也用过，不过速度总上不来让人很郁闷。rtorrent 从某个版本就开始支持 dht 了，我之前使用的时候不知道从哪里去看这个支持，速度很慢，基本就不用了。今天总算发现了问题在哪里。
rtorrent 的配置文件是 ~/.rtorrent.rc ，例如我的。
# ~/.rtorrent.rc and enable/modify the options as needed. Remember to
# uncomment the options you wish to enable.

# Maximum and minimum number of peers to connect to per torrent.
min_peers = 40
max_peers = 200

# Same as above but for seeding completed torrents (-1 = same as downloading)
#min_peers_seed = 10
#max_peers_seed = 50

# Maximum number of simultanious uploads per torrent.
#max_uploads = 15

# Global upload and download rate in KiB. "0" for unlimited.
#download_rate = 0
upload_rate = 30

# Default directory to save the downloaded torrents.
directory = /movie/download

# Default session directory. Make sure you don't run multiple instance
# of rtorrent using the same session directory. Perhaps using a
# relative path?
session = ./rtorrent-session

# Watch a directory for new torrents, and stop those that have been
# deleted.
#schedule = watch_directory,5,5,load_start=./watch/*.torrent
#schedule = untied_directory,5,5,stop_untied=

# Close torrents when diskspace is low.
#schedule = low_diskspace,5,60,close_low_diskspace=100M

# Stop torrents when reaching upload ratio in percent,
# when also reaching total upload in bytes, or when
# reaching final upload ratio in percent.
# example: stop at ratio 2.0 with at least 200 MB uploaded, or else ratio 20.0
#schedule = ratio,60,60,"stop_on_ratio=200,200M,2000"

# The ip address reported to the tracker.
#ip = 127.0.0.1
#ip = rakshasa.no

# The ip address the listening socket and outgoing connections is
# bound to.
#bind = 127.0.0.1
#bind = rakshasa.no

# Port range to use for listening.
port_range = 18204-19203

# Start opening ports at a random position within the port range.
#port_random = yes

# Check hash for finished torrents. Might be usefull until the bug is
# fixed that causes lack of diskspace not to be properly reported.
#check_hash = no

# Set whetever the client should try to connect to UDP trackers.
use_udp_trackers = yes

# Alternative calls to bind and ip that should handle dynamic ip's.
#schedule = ip_tick,0,1800,ip=rakshasa
#schedule = bind_tick,0,1800,bind=rakshasa

# Encryption options, set to none (default) or any combination of the following:
# allow_incoming, try_outgoing, require, require_RC4, enable_retry, prefer_plaintext
#
# The example value allows incoming encrypted connections, starts unencrypted
# outgoing connections but retries with encryption if they fail, preferring
# plaintext to RC4 encryption after the encrypted handshake
#
encryption = allow_incoming,enable_retry,prefer_plaintext

# Enable DHT support for trackerless torrents or when all trackers are down.
# May be set to "disable" (completely disable DHT), "off" (do not start DHT),
# "auto" (start and stop DHT as needed), or "on" (start DHT immediately).
# The default is "off". For DHT to work, a session directory must be defined.
#
dht = on

# UDP port to use for DHT.
#
dht_port = 18203

# Enable peer exchange (for torrents not marked private)
#
peer_exchange = yes

#
# Do not modify the following parameters unless you know what you're doing.
#

# Hash read-ahead controls how many MB to request the kernel to read
# ahead. If the value is too low the disk may not be fully utilized,
# while if too high the kernel might not be able to keep the read
# pages in memory thus end up trashing.
#hash_read_ahead = 10

# Interval between attempts to check the hash, in milliseconds.
#hash_interval = 100

# Number of attempts to check the hash while using the mincore status,
# before forcing. Overworked systems might need lower values to get a
# decent hash checking rate.
#hash_max_tries = 10

encoding_list = UTF-8
里面最主要的是 dht=on 和 session，这两个同时启用，才能让 dht 生效，因为 dht 需要保存 dht table 到这个路径下面。配置好之后，去 tracker list 里面看，应该多了一个 dht:// ，这就o了，还有些其他信息，可以自己琢磨琢磨。