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-rw-r--r--src/main.cpp7
1 files changed, 6 insertions, 1 deletions
diff --git a/src/main.cpp b/src/main.cpp
index 27c427f7cd..a30084a75b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4008,7 +4008,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
}
- else if (strCommand == "getaddr")
+ // This asymmetric behavior for inbound and outbound connections was introduced
+ // to prevent a fingerprinting attack: an attacker can send specific fake addresses
+ // to users' AddrMan and later request them by sending getaddr messages.
+ // Making users (which are behind NAT and can only make outgoing connections) ignore
+ // getaddr message mitigates the attack.
+ else if ((strCommand == "getaddr") && (pfrom->fInbound))
{
pfrom->vAddrToSend.clear();
vector<CAddress> vAddr = addrman.GetAddr();