I have a qBittorrent server at home that I use sometimes to download ISOs to test new Linux distros (amongst other things). The server is running 24/7 even when there are no active torrents in it. I noticed, however, that even if the server isn't doing anything, it's maintaining between 350 and 400 DHT nodes connected. I toyed a little bit with netstat and couldn't find these connections.
My question is as follows: are there any negative impact of keeping my torrenting server running 24/7 even when there are no torrents downloading/seeding? Do DHT nodes connections have any bandwidth impact whatsoever (even the tiniest) on my home network/router?
1 Answer
The bittorrent DHT is a UDP-based protocol, so it does not have connections per se. On your machine itself it will only keep a single UDP socket open to operate.
The traffic ranges in the kilobytes per second at most, so it should not have any bandwidth or latency impact on modern broadband connections.
There is one considerable resource consumption: Stateful firewalls and NAT devices - such as home routers or CGNATs operated by your ISP - will keep an entry in a temporary table for each response-reply sent to random hosts on the DHT.
On very cheap devices or with skimpy ISPs this can saturate the table and lead to packet drops when attempting to establish new connections, if you're experiencing this problem it would most likely manifest in DNS lookups failing or many different websites taking several attempts to load.
