[server] UDP Associate may not work when listening to wildcard address

[ge9]

In this UDP Associate implementation, TCP listen port number is also used as the "relay" port for UDP Associate.

socks5/server.go

Line 203 in 339b044

addr1, err := net.ResolveUDPAddr("udp", s.Addr)

socks5/server.go

Line 305 in 339b044

caddr, err := r.UDP(c, s.ServerAddr)

This will work when we specify non-zero addresses (127.0.0.1:1080 or 10.0.0.1:1080), but won't work when we specify wildcard addresses (0.0.0.0:1080 or :1080).

An option is using TCP local address.

caddr, err := r.UDP(c, c.LocalAddr())

Or at least there should be some warning.

[txthinking]

https://github.com/txthinking/socks5/blob/339b044ab0eb8485292330ab589ab4c80d8e4390/server.go#L56 NewClassicServer need to set ip, this is for udp server. for more example, see brook project source or just $ brook socks5 --help

…

On Wed, Jul 8, 2026 at 12:25 PM ge9 ***@***.***> wrote: *ge9* created an issue (txthinking/socks5#29) <#29> In this UDP Associate implementation, TCP listen port number is also used as the "relay" port for UDP Associate. https://github.com/txthinking/socks5/blob/339b044ab0eb8485292330ab589ab4c80d8e4390/server.go#L203 https://github.com/txthinking/socks5/blob/339b044ab0eb8485292330ab589ab4c80d8e4390/server.go#L305 This will work when we specify non-zero addresses (127.0.0.1:1080 or 10.0.0.1:1080), but won't work when we specify wildcard addresses ( 0.0.0.0:1080 or :1080). An option is using TCP local address. caddr, err := r.UDP(c, c.LocalAddr()) Or at least there should be some warning. — Reply to this email directly, view it on GitHub <#29?email_source=notifications&email_token=AAJPFT5NSSA3RBCUVN2MONL5DXENLA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NBYGM2DGMZWGYZDNJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAJPFT6BW4736Q3HQQCK34T5DXENLAVCNFSNUABEKJSXA33TNF2G64TZHM3TEOBQGQ4TMMB3JFZXG5LFHM2DQMZUGMZTMNRSG2QXMAQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AAJPFTY4GOLKP6TBJGECTFT5DXENLA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NBYGM2DGMZWGYZDNJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2KUZTPN52GK4S7NFXXG> and Android <https://github.com/notifications/mobile/android/AAJPFT3QYVXCVNX2AIPPVNT5DXENLA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NBYGM2DGMZWGYZDNJTSMVQXG33OVJZXKYTTMNZGSYTFMSSWK5TFNZ2K4ZTPN52GK4S7MFXGI4TPNFSA>. Download it today! You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>